Indeed though I find it silly when I buy something like a laptop (I’m probably good for a couple of years) and start getting bombarded by “hey laptops galore!”ads. I just bought one, don’t need another !

It would be cleverer to identify the replacement cycle for each kind of product and only promote stuff the victim is likely to be looking for at that point in time (after 3 years likeliness of looking for a laptop replacement is higher).

A bank transaction would not reveal what product you bought whereas a receipt would.

If prices were unique you could deduce something from a few items bought together though.

In the business of advertisements the user pays for clicks. However, it would be much more reliable for the user to pay for ads that led to actual transactions instead of just clicks.

Is there some reason for why this hasn't happened so far? (Or has it already happened?)