I don't do a lot of physical shopping, but I don't get asked for my email address. I suspect that's because I'm a little old lady and it's assumed I don't have email.
But I've been using computers since before Windows 3.1 and the internet was all text. Started off with Demon, with PoPs to dial into, with the squawking modem. 
Now with Plusnet, which operates on the same way for email. I have a sub-domain name, chosen by me. So I can have multiple email addresses along the lines of @.plus.com. The could be or or , etc. All those emails come into my mailbox. The beauty of that is that I can tell where emails have come from, and filter them if needed.
Which reminds me that I should log in to my email settings on Plusnet and re-direct all the emails to the Plusnet blackhole, because that's an address that either got hacked or got sold on, because they're almost always spam.
So, when I next go shopping to a physical shop and get asked for my email address, I'm going to do the wide-eyed and shaky response of, "oh no, dear, I don't have the internet". I'll be believed, of course, because of my little old lady status. I might smirk on the way out, though. 