Re: Annnnnnnd...
"But even when I pay with cash, many retailers will ask for a mobile phone number. Well, they don't really ask, while staring at the register they intone "What's your mobile number?" in a demanding tone of voice that assumes compliance. I've noticed that people automatically comply. But when I respond "No", there's usually a bit of comic relief when they hesitate, frown at me, and say it's for their rewards program or something like that. After a brief argument they give up.?"
They want a number? Give them a number ... any old number you can make up on the spot: yours, varied by a single digit, or a completely unrelated string of the appropriate number of digits, or anything in between. There: request satisfied with no need for argument or raised blood pressure. No privacy violation either. And it's not as if they're going to immediately call or text the number to test it. The cashiers are given their script and have to follow it -- but feel free to salt their data. I've done it for years.