I wouldn’t be surprised at this either. My DD5 is 39.5 in but with tennis shoes on she easily cleared the minimum at any of the Disney charts. Sometimes they didn’t even ask to measure her.
I don’t know about the other parks, but AK is consistent with what we had measured at home and the Dr. My son was 43.5 when we went, 1/2 inch too short for FOP. And he wasn’t able to ride.