Because Facebook wants those ads. They productize the ability to run them, and it's revenue they want. They lie about or disguise their participation in the market and their policies policing that content. Facebook continues to take steps to get more of that revenue. It's not "hard", it's just just they don't want to do it.
I'm not sure that's it. Twitter was going to be sued if they allowed one party to advertise but not the other. This decision allows them to still behave with some partisanship via their moderation policy.
Facebook is taking the safer position in this case, IMO, from a legal/regulatory perspective. It'll be interesting to see what shakes out.
There's some pretty misleading TV ads out there, especially in more purple (contentious) districts. Senate race in Arizona, for example have been brutal, and abstracted by PACs.
There are a lot of baltantly false ads on TV, and have been for decades.
Remember "this is your brain on drugs"? Or how about the "drugs fund terrorism" super bowl ads? That was a blatantly false campaign designed primarily not to discourage drug use, but to make it difficult for mainstream organizations and their people from supporting drug policy reform.
Isn't every Volkswagen ad which touted fuel economy in their diesel vehicles essentially a blatantly false ad on the issue of climate change and carbon use?
Many pharmaceutical ads have some blatantly false messaging, whether overt or not, and all of them carry the same political message: that the current system of regulation and intellectual property around drugs is healthy for people.
TV is overrun by blatantly false ads that, once you think about it, have an unambiguously political component.
A tv channel has like 6 to 9 slots per 30 minutes of content and most of those slots have the same ads playing multiple times in a day. I would guess that there’s at most 1-2 hours of unique ad content for one channel per week to review.
With user generated content and thousands of unique ad slots, using humans to verify is prohibitive.