Because they are trying to make as much money as possible. It only has to be 1% more effective and it's a no-brainer to turn it on.

Because targeting is very profitable.

Sure, but you don't have to watch the user to do that. Target indirectly via the content of the page. If I search for "Harley Davidson", it makes a lot of sense to show motorcycle ads. If I'm reading an article about curing cancer with apricot kernels, then show me ads for oncology centers or maybe for woo enhancer.

But it's more profitable to store multiple user interests & behaviors in a database to be exploited in any number of ways, including selling. The aggregation even lets you infer other valuable information about the user, such as the scandal with Target inferring pregnancies several years ago.

Sure, it's generating an incredible amount of profit for a few companies in California.

so effective advertising does require surveillance? Is there way to to know if companies like FB would be sustainable without surveillance or would they simply die out ?

in other words, would banning surveillance business kill FB, Google ect? Would we still want that law if that was the case?

newspapers, have done just fine without it for several hundred years. Radio and TV likewise can't do it.

Duck Duck Go doesn't use it and they do okay. There is a lot more money in surveillance based advertising, but it isn't the only way.

> Duck Duck Go doesn't use it and they do okay.

Right. My point was FB/Google would cease to exist in their current form employing hundreds of thousands of ppl and responsible for US tech domination.

Would we as a society ok with losing all that and turning FB into a 100 ppl company that no one cares about.

It hasn't been technologically possible until recently, and now that it is, businesses are strongly incentivized to use it, in order to keep up with the growth of competitors that do used tracked advertising.

Privacy-focused mass-market products like DDG and Firefox will very rarely be able to keep up with the giants that prioritize profit. As long as users disregard their privacy, there'll be businesses ready to entice them with customized features, and of course advertisers will reward that too. That's why regulation is the only real way out (GDPR, etc.).

This isn't an all-or-nothing proposition. Tracking-based advertising isn't used out of necessity any more often than negotiating a $200k TC increase is. It's about maximizing profit, not simply about sustained survival.