@RobertH,
I believe what you are talking about. A person’s zip code can indicate a certain level of wealth. Also, job information. (Yellow pages, public info. - I’m dating myself here.). Property information is public at the local “registration” government office. It’s public record what a person paid for his/her house. (I said registration, because I’m tired after work and can’t think of the proper clerk department name.)
Though I can’t prove it, I think Disney tried something like this with me, years ago, over booking a hotel and prices offered. That story is too long to detail here.
Politicians also use computer collated data for campaigns.
I guess when you place an item into an online cart - the company (Amazon) is hoping that you won’t notice the price increase when you click on purchase. Or, that you have already committed to the item no matter what.