Disturbed

Went to order food today and while standing in line my 4 year old son needed to use the bathroom. I know they dont have a public bathroom and could have just said no but I expect some sort of human decency as its just a small child. The lady working did say that he is allowed to use the bathroom and opened for him. We were on our way in when she stopped me and said that he has to go alone and I am not allowed inside. He is a 4 year old child. The more he kept asking me to go with the more the lady told me I am not allowed to go with him. Which made me wonder, why would they think I would let my child go to the bathroom alone with a stranger. You hear so many stories of children being abused. And other than that, what was going on at the back that they so strictly refused me to go inside with hom just to use the bathroom. We endee up running to the store next door where they very friendly showed me where the bathroom is. So what goes on behind mochachos closed doors that they dont want adults at the back and they want to take children to the bathroom alone?