Probably that's one of the negative effects of the latest technology. We can't even find enough privacy because most of our personal information even our appearance could be tracked by apps like Facebook. However, we could do something to get rid of it. There are privacy settings that we just have to check.
I think the privacy settings are just to give the illusion that they are not tracking you. There is huge money in personal data, and what is now being called surveillance capitalism. Tracking through FB posts is only the tip of the iceberg. Anyone who carries a modern mobile phone is giving their location to these companies 24 hours a day, and there is nothing you can do to stop it. All browsing history is tracked. A major aim with FB's new Libra coin is I'm sure to suck up data on purchase history, too.
So they get all this data, which they sell on to third parties, advertisers and spam mailers, for profit. But it's more far-reaching than that, they use all this data to build up a profile of your personality, your interests, your web of personal relationships, your preferences and biases... the aim being an ever more accurate digital representation of you, in order to better predict your future behaviour. FB and Google seem to be the worst two offenders, but it is spreading. Advertisers pay a lot of money for this information.
It doesn't stop there, either. FB is particularly egregious in regard to using this information to modify your behaviour, most notably in curated newsfeeds to channel you into voting for a certain party. Google do this as well - take Pokemon Go, by "Niantic", which was spun out of Google - a restaurant only needs to pay a few dollars to lure a rare Pokemon to their establishment and they will increase foot traffic and sales dramatically. So this thing is dressed as a game, but is quite clearly a means to modify consumer behaviour.
I'm in the EU, and thanks to GDPR legislation, we now have a better idea of what is happening, even if we can't stop it. Every website now gives you a cookie warning, and if you delve into the permissions you're presented with an endless labyrinth of client companies who then sell the data to their clients, etc, etc. But people just click 'ok' to accept everything. Even I do it sometimes, it's everywhere, it wears you down. You can use VPNs and ad-blockers and everything else, but the attack is just relentless and omnipresent.
There's a ton of information out there once you start looking. Take this article from 5 years ago - imagine how much the tech has improved since then!
https://www.theguardian.com/technology/2014/jun/29/facebook-users-emotions-news-feedsSorry, I'll stop ranting now. Don't trust privacy settings!