If Google is practically speaking the gatekeeper for these kind of shady dealers (because it sees both the consumer demand and the bad actors), then the most efficient system is one where Google is given both the responsibility and the tools to do the regulation.
In fact, Google might be in a better position to regulate this than the states are. What should the states do -- individually browse for ads on Google and then call up those places? This still places Google front and center.
This is the same reason central planning is a horribly inefficient system -- yes, in principle you can have the entire economy send their data to the central government, then the central gov't comes up with a plan and redistributes it to every factory -- but in practice a lot goes wrong in putting so many links.