Yet somehow print/TV worked for decades just fine without spying on their users.

I do not want the gas station, or the airplane I'm on, spying on me to build relevant advertising. That is the end game of "relevant ads": my gas pump already serves me ads, the airplane I'm on serves me ads, my own car now (via a software update that occurred after purchase) serves me ads. Monitors now serve ads. TVs are abusing people's Internet connections, which isn't ads, but it's basically the same problem: if I can abuse the customer without consequence, why shouldn't I?

Just no. The problem is, I as a consumer cannot vote with my wallet: companies can and will go "I could take your money, and earn $X, or I could do that and ads and earn $X + $Y."; there is not reason for them to choose the former, and most markets are so concentrated (e.g., airlines) that there is not ample competition for the market to provide ample "vote with wallet" choices. Further, in the car example, it's just bait and switch: even when I think I can vote with my wallet, the company can just alter the terms of the deal, knowing full well the switching price of a car makes me subservient to them.