Blu-rays are compressed. "Zipping a zip file" doesn't apply here because zips are lossless. Video encoding is almost entirely lossy, and there's a lot of tradeoffs to be made between file size and quality. The whole point of the more efficient codecs is to minimize the quality tradeoff. There's also a bunch of parameters to tune the resulting bitrate which is the #1 factor in deciding the final filesize.
That being said, I'll agree that the least quality loss will come from using a Blu-ray remux since those are very high quality.
Blu-rays are compressed. "Zipping a zip file" doesn't apply here because zips are lossless. Video encoding is almost entirely lossy, and there's a lot of tradeoffs to be made between file size and quality. The whole point of the more efficient codecs is to minimize the quality tradeoff. There's also a bunch of parameters to tune the resulting bitrate which is the #1 factor in deciding the final filesize.
That being said, I'll agree that the least quality loss will come from using a Blu-ray remux since those are very high quality.