To be fair, it's just withholding - so if you file US taxes indicating you're a non-US person, you should be able to get a refund. But yeah, definitely not fun to have to file that form every three years. I think my husband put a recurring calendar invite for us as a reminder, and if he hasn't, I'll have to remind him to, ha.
Non-resident stuff is always really annoying. When we lived in the US but rented out our condo in Canada, we had a process where every month we had to submit the taxes on the gross rents to the Canadian government. Then, early in the year, we'd request a form that basically was "how much tax did we give you?" which was kind of ridiculous because we were the ones submitting the gross rents every month. It always took them forever to generate the form that told them how much we had already paid them, and then we could file expenses and get a refund based on net rather than gross.
Really really annoying.