as someone that has spent the past week working through different distros to figure out what I want to move to here is my list. Note that this is all coming from someone that actively wants to switch and not someone that doesn't realize there's other options like some of the other comments are getting at. This does not obviate everyone else's comments that linux just needs to come preinstalled on stuff or that manufacturers and developers need to do more. Both of those are a given, but those are not something that distro maintainers or kernel devs can control.

audio doesn't work properly on half the distros I installed (linux mint, zorin both had popping and crackling anytime I played audio)
video doesn't work properly on many of the distros I tested (youtube being blurry is one example, zorin os couldn't run games at all really). I understand this is a driver issue. But on mac I've never once had to maintain any driver, stuff just either worked or didn't work. On Windows the most I've ever had to do was run an installer or uninstaller to re/un-install whenever something went wrong. Every distro has a different way of fixing drivers, and every help article is just "try this if that doesn't work try this" for 15 different options. Here's the thing, this isn't something for driver maintainers to fix. Bazzite and CachyOS both have no audio or video issues, so it's clearly working in some manner for the hardware I have, it's just that some distros have it working and some don't.
choosing a distro is not as easy as loading up a usb with the live image and starting it up. lots of times things do not work properly in the live image, or they work differently. So testing out that way can give you errors, missing dialogs, etc. An example is CachyOS: in the live image (in CachyOS Hello) you do not get the "Install Gaming packages" option and as a result you might do what I did and try to install them a different way, resulting in broken Nvidia drivers or error messages that no sane person will ever take their time to figure out, they'll just switch back to windows or mac.
to expand on that point, lots of times testing in a VM would be a good way to see a new OS and that hasn't worked for me a single time. Even more issues with that when I was testing Bazzite. Bazzite runs normally on its own partition, but in a VM it was terrible. Only way to figure this out is by installing on a partition and testing from there. That's another friction point. The reason this is a friction point is because the common suggestions from the Linux community is that you should "find a distro you like". No sane person is going to partition their drive into several 100gb sections like I did and test each one on an actual install rather than just testing on a live image. I know that because I have a bunch of non-computer friends and they want to switch to linux for the coming windows apocalypse and are just not going to because of the perceived difficulty. In my experience over the past week (and I tried this earlier this year as well) it's not a perceived difficulty. It's an actual difficulty.
Testing multiple distros requires partitioning your drive up a bunch, which means dealing with bootloaders, which means dealing with grub vs limine vs rEFInd vs systemd etc. No sane person who has no computer experience is EVER going to understand these options. I don't understand them and I run 20+ websites, have several (linux) servers at home, and have dealt with computers for decades. One issue I came across was that the CachyOS installer doesn't make it clear that you have to choose your EFI boot partition so that it's not the windows one, at least if you've already installed other linux distros (like I had). So I spent several hours trying to understand why the install kept failing (and according to the CachyOS instructions if it fails you have to completely reboot the live image due to the installer not unmounting the disks properly, which was another 30 minutes of troubleshooting) and it turns out that it was trying to install the bootloader onto the windows bootloader rather than the already existing grub bootloader from mint and bazzite.
testing multiple distros requires understanding SO MUCH about how linux works that it's just really not feasible for anyone. So it's not just about choosing the right distro, but you have to get the right distro on the first time which means that every distro needs to work out of the box immediately. Which just isn't the case.
too many ways to install applications. Several other comments have covered this and then people respond saying that windows and mac have multiple ways to install things when really that isn't the case. On windows 99.99999% of installs are going to be .msi/.exe. No normal user is installing chocolatey or winget packages. On Mac there's two ways to install things and they're always covered by the website: App Store or download and open and the file structure will literally tell you how to install in a nicely packaged window. Usually this is just "drag to this folder". Sometimes it's 'double click this installer'. On CachyOS there's no fewer than 6 ways to install things that you will get suggestions for: 1. Octopi 2. CachyOS Package Installer 3. pacman 4. paru 5. yay 6. tar.gz download. On Bazzite the options are completely different because it's Fedora based. On Mint it was another set of options. Users are required to understand the underlying distro's installation methods in order to figure out how to install stuff properly. Not only are they required to understand that, but they've got to figure out which install method for any given piece of software. For example, installing Dropbox one way vs another can make it work completely differently, including worse. Installing Spotify pops up a KDE Wallet dialog that users are expected to know how to manage.
system dark/light mode switching. I still haven't figured this out. On mac it's built in. On windows I just double click installed Auto Dark Light Mode or whatever it was called. On arch apparently I need to install darkman and then set up some scripts and I have no desire to do that. Why isn't it a single button like Mac? or at least 4 dropdowns like Intellij/other jetbrains products, where you just choose your light mode and light mode editor theme and dark mode/dark mode editor theme. I know there's something in the works, I've seen people talking about how this is a desired functionality, but wasn't everyone complaining about how wikipedia didn't have system dark mode for like a decade? And linux is still behind that? User's have to manually write shell scripts to get dark mode to turn on at night?

I wrote this the other day and never finished it, but that's just the stuff I've found so far.