Back what up? Grocery stores send out thousands of coupons every day in the regular mail. Coupons are price discrimination plain and simple. I’m honestly not sure what you need me to provide to show you how coupons work.
Grocery stores getting more sophisticated: https://www.forbes.com/sites/moneybuilder/2012/08/21/individ...
Here’s airlines: http://theconversation.com/a-travellers-guide-to-airline-pri...
There’s a bunch of examples right in the fucking wiki page on price discrimination: https://en.wikipedia.org/wiki/Price_discrimination
Please spend a little effort at least googling before you make demands for proof of something so common.
> From your comment style and prior history
That’s just pathetic. Nobody is ever impressed you read someone else’s comment history to make a childlike ad hominem attack, especially just to misuse the term “red herring”. Stalking has ever advanced a conversation. Stick to the topic.