Google is the only organization with the data to show this happening at scale and they don’t have incentive to connect all the one-off anecdotes.
So while it is risky, not sure how they could be caught. I don’t think they are running click fraud bots, but it’s hard to quantify how hard they work to stop them.
A friend of mine estimated that 1/3 of ad spend is click fraud but it’s just in the wash because it’s hard to stop.
Google's advertising business is built on trust. The moment there are a few scandals involving fake/robot ad clicks, big advertisers will remove their ad campaigns.