[echlebek]

What happens when another person wants to use the toilet? Two possible scenarios.

A) They have to wait 5 minutes (pointlessly) plus the duration of the next person's stay. B) They pay to bump the person behind in the queue.

Both scenarios are bad. In A, the toilet is not being used to its effective capacity. In B, paying customers can prevent non-paying customers from ever getting to use the toilet.

Toilets should be provided for free to customers by private businesses, and to the general public by cities. The alternative is alleys reeking of urine and feces. Toilets: a worthwhile public expense.

[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.