They have the resources to hire a vast number of people. So yes they probably could manually review every ad. And either way it is their problem to solve. They are not entitled to be hugely profitable or free from the obligations that smaller organisations have.
Surely there is no need to review every ad. Coke and Apple and whatnot are not going to be doing this. New companies or companies with a history of complaints can face extra scrutiny. With AI capabilities so far along you have tier 1 ready for free…
Every advert for TV and radio has to pass a review in most jurisdictions. Billboard laws vary wildly, but some also require a review.
Why not ads online? The industry would adapt pretty much overnight, because it is something everyone already does.
Yeah, like $5 per unique ad would be basically nothing but it would pay for plenty of review.