Proper footwear

I was working out the other day and I saw a guy walk in to the gym wearing flip flops. No big deal, he walked into the locker room so I thought he was gonna change and then proceed to exercise but I was wrong. When he came out he walked to the bench press area and started working out like normal. That is an accident waiting to happen and I wonder what the guy was thinking? He can't do cardio in flip flops and I dont want to see some nasty toes on the leg press machine. I wear boots to cover my feet for protection and it gives me a few inches since I'm so short. I know its not a rule but I think all gyms should make members proper footwear and flip flops should not be allowed!!