Because you don't own whatever is being used to advertise. It's not your decision to make. They can charge you and then show you ads.
>In short though I believe there has to be a fundamental shift from the belief that ads, tracking, and shadow profiles are the path to profit in an increasingly connected world.
Belief doesn't mean anything. What matters is what pays the bills. If alternatives worked well, then I'm sure we'd have plenty of sites that would already be doing this. You could argue that crowdfunding is one such route, but I don't think that will ever work on a large scale. The amount of money required just isn't there.
The reason ad-tech is so common is because people are unwilling to pay any amount of money.
And I agree that pay-as-you-go would put a high mental overhead on sites. That's why we have ads instead.
At least then I’m actually choosing to receive ads. In return it would be nice to have a say in the sheer amount of attention grabbing advertising we’re subjected to in the physical realm. There is no consent there, and this advertising only serves the purpose of businesses selling stuff. Why can’t I charge a cost per view for everything shoved in my face on the way to work, or at the cinema, or on the train, or in any other situation where I’ve already handed over cash? My attention is a scarce resource that holds a lot of value to my friends, family, colleagues, and any other human being in my life. I’d love to paywall access to that.
In short though I believe there has to be a fundamental shift from the belief that ads, tracking, and shadow profiles are the path to profit in an increasingly connected world. Something about the relationship needs to change, maybe towards business-2-citizen instead of business-2-consumer.