I think generally the opposite is true. A place with bad coffee but great decor can charge the same as a place with good coffee but crappy everything else. And so to maximize profitability, it does just that, meaning that at any price level, the place with the worst non-coffee has the best coffee. If you judge them by their posters, then what you’re paying for is the posters.
I think people complaining about AI art at businesses are making an aesthetic argument and then laundering it into ones with more heft. I mostly agree with the aesthetic argument, but it’s only that, not some wider indictment.
You could literally have a blank piece of paper with the word "coffee" printed on it in times new roman and it would look better than off ratio AI slop graphics. It's not a case where better necessarily costs more.
I also think that you are assuming here that the effort not spent on good signs is being spent on good coffee. That might not be true. It might be spent on nice chairs, or it might be being spent on pastries, or on non-coffee drinks, or one of the many other things a coffee shop can focus on. In fact even if coffee, maybe they do brewed coffee and espresso based drinks and cold brew and milk oriented drinks and milk-substitute oriented drinks. Which of these are they spending effort on?
The thing about coffee shops is actually that they tend to do a lot of things, and so unless they do almost of them well there's a good chance they don't do one of the things you care about in a coffee shop well. Consequently it makes sense to say "given that you don't do this thing well, there's a good chance there are other things you don't do well and those things might be important for me in a coffee shop".
I think people complaining about AI art at businesses are making an aesthetic argument and then laundering it into ones with more heft. I mostly agree with the aesthetic argument, but it’s only that, not some wider indictment.