As a rookie teacher, I gave bathroom passes freely and ran out within a short time. So I made a reusable pass, as other commenters have described.

Soon, the admin got wind of this and told me to stop. They said I needed to control the kids better. This was one instance of my "lack of control," there were many others. For example, I allowed kids to go to the library whenever they wanted, and to sleep in class if they needed to. All of these were written up, and my contract was not renewed.

There was the time a kid puked on the floor. This was in high school, not in elementary school, where interoception (the sense of one's body state and needs) is still developing, and such accidents sometimes happen. Shortly before that, I had gotten chewed out for giving out too many bathroom passes, and was told, "If a kid says he's sick, tell him to hang his head out the window." I shit you not.

If some teachers are monsters, that's because the admin forces them to be that way.

I no longer teach in the classroom. My tutoring clients tell me I ought to be in the classroom, I'd make a great teacher. If only they knew ...