Upwards of half the ads I see on YouTube are obvious scams. There's no way nobody at Alphabet is aware.
Of course they know. They have no civil or criminal consequences for engaging in a conspiracy to commit large scale wire fraud, so of course they just let it happen, because who wants to speak up and cause the metrics to go down?
This also incidentally has the effect of making their business less profitable, so arguably it’s your moral duty if you can do this at no cost to yourself.
It really depends on the platform and your country’s consumer laws. Some platforms force a return which makes this whole exercise not worth it.
So it still works, in some ways :)