• It is lighter and cheaper, as you can use thinner materials. This is because pointy is a stronger shape than flat.
• It gives more interior space.

If you're using lighter cheaper materials you'll need all the added interior space for roof trusses, none of it will be livable space.

• It allows more sunlight to reach the street.

No, for the same amount of occupiable space the shorter flat roof blocks less light than a standard 10:12 or 12:12 roof

• It has a smaller area-to-volume-ratio through which heat can escape.

The greater surface area of a pitched roof means this is absolutely not true. The hypotenuse is always longer than either leg.

• Solar panels get a higher efficiency.

This one actually depends on latitude, equatorialy it's better flat. And don't forget that the minimum summer angle is limited by the pitched roof.

• If a city has the same height restrictions for flat roofed buildings as for pointy roofed buildings, and the architect is too lazy to go to the city council to explain to them that that doesn't make sense, the architect can design a building with more volume by making the roof flat.

No it makes perfect sense. It goes back to your comment on letting sunlight through to the street. The maximum height is the maximum height so everyone gets the same amount of light.

In other words: ~~the only reason any architect would design a building with a flat roof is because they are either lazy or they have no idea what they are doing.~~ this guy thinks their habitat is the only kind over the whole planet and can't imagine people living in areas where snow load wouldn't need to be considered.

Flat roofs are good for putting large unsightly equipment on, particularly AC units

The A-frame is peak house design in cold environments and I refuse to hear otherwise.

Have you ever tried to explain anything to the city council? They're extra neurotypical popular people and will not be honest with you. You'll say "I want nicer roofs because reasons" and they will completely make up reasons for not liking the better roofs. Maybe they're being bribed by a subset of landlords, or they're just racist, or they're holding out for something unspoken in exchange that you should know about already.

People in political office are not refusing to change because they haven't heard enough good arguments. People who don't get the change they want are not just lazy.

Most modern flat roofs (at least in my neck of the woods) aren't actually flat. They're at an incredibly shallow pitch. In residential applications (after underlayment) we use high density foam slats that get put together in a grid formation, each piece gets slightly narrower on one end until they can properly fit under a piece of bird stop around the fascia. Before the bird stop goes on, the foam is sealed with a waterproof self adhering material that comes in huge rolls. When properly installed, they can last 15-30 years. Just as long, if not longer, than any shingle roof. There's also high density polyurethane foam flat roofs that can be sealed and are able to last up to 50 years. Many commercial operations use these methods as well as hot tar mopping, which can basically last forever. The one drawback to flat roofs is load bearing difficulties in places that snow. I don't know much about that but seeing as flat roofs are everywhere in the north too, it must not be too difficult to work around.

Don't get me wrong, I love a good tile roof too, but there's plenty of beautiful structures with flat roofs out there. And tile has considerable draw backs as well. Tile is incredibly heavy, they're very fragile, they're ludicrously expensive, and they're expensive to maintain.

On the rain, no roofer is working in the rain, and tile roofs are vulnerable to rain during construction too. When it's down to the plywood, you're as likely to have rain troubles as any other roof. You can lay shingles and foam for flat roofs when you're dried in too, but no one will if it's more than a drizzle. Tile becomes an active danger in the rain because most tiles get really slippery in the rain

Replacing broken tiles is a bitch and a half, you have to carefully dance between tile joints and one slip of your foot (which is likely during repairs because tiles are slick and can become moldy/slimy when not maintained properly) you're likely to break another tile, leading to more work and more chances of another broken tile. Even the process of removing a broken tile can break the tiles surrounding it

Tile in general is really finicky, high maintenance, and requires unique tools, methods, and skilled laborers that are capable of doing the work. That is by no means a bad thing but it's really easy to get a flat roof that does the job perfectly fine. Tile, not so much

Roof decks are awesome though...

I like flat roofs because I want to be able to use a roof for a deck. Though, full disclosure, I don't know how bad the leaking is and I don't live in an area with snow.