The fallacy in your argument is that the average home buyer has the time or expertise to (critically) evaluate different home inspectors.

Do they need to hire an inspector? Yes.

Should the inspector have insurance and a certification? Yes.

Beyond getting recommendations from friends and your real estate agent, the typical home buyer mostly “doesn’t know what they don’t know.” - which is why they’re paying $500 to someone to do a basic walkthrough of a house.

This extends to all sorts of areas of our lives where it’s basically impossible for an individual to be fully informed, at some point we make a judgement call and make a decision.