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. In this aspect we might as well ask why the others are considerably worse - but the problem is still there, we’ve been relying on a single search engine to find stuff for us, and that’s a big issue with a system that was supposed to be as decentralised as the internet.