Flawless software isn't the goal, ever. Feature development is almost always the primary goal, and fixing bugs and performance issues is only done if the bug is bad enough.

Like the old quip that a cup of coffee lets you do stupid things faster.

Lack of information. When you are on the building side you become blind to its faults. Consumers almost never tell you what isn't good about it.

> why is it all still so buggy?

Also lack of information. I haven't seen any bugs in years in the things I've worked on. LLMs have closed every last obvious testing gap, squashing any outstanding bugs there. That's not to say it is all bug-free now, but what bugs users may be experiencing aren't being reported.

AI is good at building software, but it is still not good at consuming software like actual consumers do.