Dash cams are much more tightly regulated in the EU than elsewhere (you become a Data Processor and have all the responsibilities that comes with that).
Private ANPR in public spaces is unlawful in I think every EU state?
Coming from an American perspective (where, when you are in public, you have basically no expectation of privacy), this seems insane.
Does this mean that if I'm filming a vlog at Brandenburg Gate (which inevitably includes video of other people in the background enjoying the area), I'm in violation of privacy laws?
Does that mean if I take a video selfie of me and my family members (which, again, includes images of others in the background, and which is automatically uploaded to icloud) I'm a data processor and am in violation of privacy laws?
I assume there is some line here, but I can't think of the logic separating a person's dashcam from my examples?
As anyone who has gone to law school will tell you, you can only acquire the title that the seller has. If seller stole the goods, he doesn't have any title, so he can't transfer title to a subsequent buyer. See, e.g. UCC § 2-403
There are exceptions when it comes to those who have voidable title (thieves do not have voidable title).
There are also cases where courts have more or less created exceptions close to those OP has described. For example, if Best Buy receives some stolen merchandise and sells it to good faith purchasers, courts have held that the victim needs to pursue the thief/Best Buy, not the end purchaser.
But generally, OP is wrong: if you buy a stolen bike at a flea market, you don't get title and the owner can get the bike back. Think of the policy implications if the rule was as OP claims. All thieves would have to do is immediately sell stolen goods and the owners could never get them back. That would be absurd.