> There's an obvious catch-22 here: either you are maintaining privacy, and the sponsor has no way to know whether their segment was viewed

The same way they did in the past, with broadcast radio and television: they base it on audience numbers rather than tracking whether people actually listened or viewed the ad. Besides, isn't one of the major motivators of tracking to avoid fraud? (Which I find ironic, given I don't view advertisers as very ethical in the first place.)

> Either way I fundamentally disagree with them on the idea that push advertising is ethical in the first place

The way I think of it: advertising doesn't have to be unethical, but it incentivizes unethical behaviour.

> Like did you also not fast-forward your VCR through ads in those days and instead dutifully watch attentively lest God know you were naughty?

I would typically walk away to do something else. Same outcome though. That said, I started to turn away from broadcast media in the early to mid-1990's. I forget whether it was due to advertising, but the end result was a lot less exposure to advertising. Which is a good thing IMHO.