The distinction is the expected ratio of US customers to international ones. A significant inconvenience for a select few customers is nowhere near as bad as a small inconvenience for every customer.

Also, shipping is _important_. Definitely agree with that point - if you spend all your time making the checkout form internationally friendly, you've already run out of time for your product. You're either irrelevant, hopelessly behind the competition, or completely out of money.

Might be viable at a large company, though, where you've got people who are already doing nothing useful.