If I look for “cat sweater -dog”, I’m going to get nothing but dog sweaters.

I tested this out, and I consistently got cat sweaters:

so odds are that the boolean handles issue is either messier (triggered under more specific conditions than in your example) or already fixed.

That said, I do agree with you that quality is one of the factors here; since Google search is considerably better than the alternatives, it feels no pressure to improve. But the problem is still there, we've been relying on a single search engine to find stuff for us, you get users learning how to work around those issues of that single search engine, and they won't be solved.

[Completely off-topic]I can't picture my cats using a sweater like this for more than five seconds. One would go full "cat.exe stopped working" and the other would shred it into pieces.