Really does seem to be the case. I just tried with The Omen and was given a list of countries. Next to the US was an ad to "Stream with NordVPN", suggesting that's the only way to view it here. However, I clicked the Hulu button, and it said US without the ad. Sure enough, I checked Hulu itself, and it's there—no VPN required.

The ad placement is confusing. Hopefully it's not intentional. JustWatch may not be as clean and may have ads of its own, but its entry for the same movie has zero confusion.