That's probably a good idea. They can also earn interest on the deposit. (Not that they need the money).

I used to flag obvious scam adverts. A bunch of times I'd even get an email response a few weeks later saying it was taken down. But then I'd see it again (maybe slightly different or by a "different" advertiser, who knows). Its whack-a-mole.

The reality is that google profits from scam adverts, so they don't proactively do anything about it and hide behind the "at our scale, we can't effectively do anything about it" argument. Which is complete horseshit because if you can't prevent obvious scams on your platform, you don't deserve to have a platform. Google doesn't have to be running at their scale. "We would make less money" is not a valid excuse. We'd all make more money if we could ignore laws and let people be scammed or taken advantage of.

There's plenty of ways they could solve it, but they choose not to. IMHO this should be a criminal offence and google executives should be harshly punished. Its also why I have a rather negative view of googlers, since they wilfully perpetuate this stuff by working on adtech while nothing is being done about the normal everyday people getting scammed each day. Its only getting worse with AI, but I've been seeing it for years.

Use their Recaptcha to let users identify scam ads instead of cars and traffic lights.

They can, but as long as regulators let them get away with it, they will just pocket the money instead. Google are, imho, an evil company.