[chanz]

If there is just one toilet, then yes those scenarios are the worst case to the idea.

So if a toilet needs a queue, then the first in-first out method should be used to prevent someone from bumping the queue and prevent over excessive wait times for someone who can't pay.

Also if they want to pay for the toilet, they can always pay for who is in front of them.

To enforce such rules is always a problem, but so are all rules in our society.