I guess "often" is relative, but this happens to me pretty regularly.
I live in Canada, and it's not always obvious if an American company ships here or not. If the answer isn't trivial to find, I'll do this:
1. Add something to the cart
2. Start the checkout process as a guest
3. Fill in the boxes that pop up during the checkout process
4. Close the tab when I see that the country dropdown only has USA available
On most websites these days, you're asked for your email before your mailing address. And after I abort the checkout, I'll get an annoying "Psst...you forgot something in your cart" email a few hours later even though I never made an account or placed an order with my email.Stores built with Shopify do this so consistently that I have to assume it's an out-of-the-box feature you need to opt out of.