I think you're underestimating some of the ad products. Video ads are very lucrative. Facebook auto play's ads and their measurement is usually how long it actually plays. Facebook's native advertising, is very effective when targeted properly. Most people don't realize its an ad.

For google Impression based advertising is still huge, and growing especially on mobile apps/games. Youtube's and mobile video ads again, like facebook is very lucrative. Most of the time these video ads can't even be skipped. Also context based search is still huge. Most people will click on the first link of a search regardless if its an ad or not.

So its really less to do with click and more about views.