I 100% understand - if I stayed there, I'd want that rule in place too. It's only right that resort guests are prioritized. Plus, I enjoy walking - it's cooler and so beautiful this time of year. (It just helps to know if the best Halloween decor is usually concentrated on particular blocks, as there's no way to cover the entire place and I'd hate to miss the best displays.)
Maybe one day cart "sub-rental" will be a mini side hustle for resort guests: rent your cart to a guest for 1-2 hours and make some $ to cover dinner. (Or host a personalized tour for couples.)