Here in Mexico, 60 is considered a senior for national resident discounts. The fast-track service is for anyone who may have a mobility issue at the time of flying, they don't check for your age. Also, because some of the gates are very far away from baggage claim. The same applies for going to a gate for departure. You would flag down one of the guys with a cart outside and they will radio a person with a wheelchair and they will take you through the check-in process all the way to the plane door with all your luggage. For regular folks those guys can still help at baggage claim if you have a lot of bags that require a couple of carts, they will load them and escort you to the taxi stand where they will load all your bags. I used them for that purpose when I moved here.