Not macOS but my iPhone is struggling with space to update and there’s a ton of data I just can’t delete like data X stores somewhere or WhatsApp that duplicates photos in addition to a massive amount of system files that aren’t specified.
This lets the system clear space for large downloads like this. You just have to know which options to enable.
Which is weird because many manufacturers don't restrict flashing a different rom, and even with standard Android you have more access than iPhone gives you.
Manufacturers don't, but app makers do. I know people running on LineageOS that have to keep a second smartphone on stock Android for their banking authenicator app (which fails on Lineage because it's not the manufacturer-supplied ROM and that supposedly means it's been hacked).
I agree though software updating is widely inefficient given how it could be done.
For example, Apple Watch series 3 cannot update without replacing the whole system for at least 3 years. In this case they didn't even sell more storage.
In the end, whatever; it's just Apple nonsense, better be done with them and look for hardware elsewhere than care about all this...
Apart from that, the bigger issue is that this is something that affects many users and the selling point of Apple was always that it should just work, which it clearly doesn't in this case.