I think that is probably not a common enough use case to optimize for. Additionally it would be easy for a user in that position to just search "shirt" and ignore the occasional striped one, or to search "polka dot" and "paisley" seperately

That sounds like a lot of repetitive searching. I wonder if we could get a computer to do that for us.

I understand the point, but there are plenty of bigger fish that I would want Amazon and Google to fry before spending their engineers' time on a triviality like this. I just don't think that having to make three queries instead of one in this occasional situation is such a big deal.

You're arguing the search is "good enough". Because we can adapt to the machines. But the company who will not force us to do so will get our business. The company who creates the best digital butler will win. They know this. They try hard. And they still fail at simple stuff when judged by humans.

Another possibility is that maybe it really is "good enough", and they get a bigger advantage by competing with each other on more important aspects of usability than these kind of trivial issues