I suppose if the government felt that ads-supported search engines had such misaligned incentives that it would be net beneficial for society to create one without such incentives, then that might serve as a justification. I don’t actually think this is plausible, just making an analogy with say private fire departments.

So that search engines work.

Google search has been crippled by ads. Sometimes people just want nice stuff and a search engine that wasn't designed to mislead (https://www.theverge.com/2015/11/20/9768350/google-ads-searc...) and where the amount of money paid doesn't dictate what is easy to find would be a great asset to everybody. No company has risen to give us a powerful search engine that isn't also a cesspool of marketing bullshit so it would be reasonable for people to seek an option that serves the interests of the public.