Destination Wedding

Probably some kind of package deal they want you to sign up for. They likely want to prioritize the groups that also book hotel stays in addition to the meals. Room stays have much higher profit margins than food so not surprised they would prioritize those.

When I was looking at weddings in Mexico, it was that if you wanted certain items to be free for your wedding, 80% of guests have to stay at the resort. I would call around at a few different hotels and explain your situation. Surely, they must host weddings besides those from outside the country. And if they say you are technically out of the country so it has to be considered a destination wedding, I would just have the local family book a wedding.