Bing is the easiest to buy programmatic access to.

But I think they don’t tell you because they sometimes use residential proxies to scrape search results the same way they used residential proxies to scrape the web.

There are a lot of search APIs for AI these days.

They really are not inferior. There are many different APIs with different strengths and there are aggregators on top of them that produce results that are significantly better than Google's. Everytime I accidentally use Google I'm shocked at how terrible it is.