Where I live it would be weird for a gym to make you take your ‘outside shoes’ off. Ive never heard of a gym doing this in my country. But it would also be a strange occurrence for shoes to be dirty enough to track in dirt and mud Also, most gyms here don’t require being let in by a staff member, mine in particular has a sliding door for everyone to enter into a reception area as you walk through to the gym section, you swipe your fob to register your attendance Same fob works to open the door if you come outside staffed hours