And very easy to automate. We know they can do it. But until there is sufficient threat of action if they don't then they are happy to let their users get fleeced in exchange for the advertising $.
There is an argument that "if they crack down on the easy to detect stuff, the scams will just get more clever" but that is not at all why they aren't making more effort.
One funny thing I've noticed with facebook, is that if you start responding to such adverts with comments along the lines of "this is obviously a scam because..." responses, they start showing you more and more of that sort of scam presumably because you have shown engagement with the previous ones.
"Not OK" is forgetting to clean up your table after the meal. What these scammers are doing is simply fraud and Facebook should be liable as they enable it.
I remember when I set up my first FB ad (maybe 10 years ago?) it took a few days because some of them were manually reviewed. Fast forward 10 years and they accept any fraudster who pays them a few bucks. Just low scum, that's all.
This is just not ok. I understand that screening everyone in the world's personal posts/shares for 'fake news' is a daunting task, but KYC-ing advertisers and screening/auditing ads for blatant and obvious scams or false marketing is many orders of magnitude less resource intensive... and should be required by laws with teeth.
If the costs of doing so mean that it's impossible to make a profit as an ad platform, then that business model should die.