Weird Places People Here Wear Slippers

Everybody tells me that part of the bonus of living overseas is learning about all the nuances of a culture. In the Philippines, one of these lovely nuances is the practice of wearing slippers (flip-flops). It is hot here and during the rainy season (just ending now) it floods a lot so seeing people in the streets and malls wearing slippers seemed very normal--much like the states in the summer. There are however some weird (to me) places people wear them. They are as follows:

1. Surgical Nurses in the O.R. They wear them with socks and the little surgical booties but still weird.
2. Construction Workers. Can't be safe.
3. Tricycle Drivers (pedicabs). Don't they worry their toes will get caught in the bicycle wheel spokes?
4. Bank Tellers. Just looks weird to me to see a suit coat, skirt, blouse, and slippers.
5. Garbage Men. Can't be healthy.
6. Janitors. I am specifically referring to people cleaning the sides of roads and freeways. Can't be healthy or safe.
7. Cooks. Can't be safe.

Thing that is still weird to me about all this is I got kicked out of the LTO (DMV) for wearing slippers, yet they are allowed to be worn at work at all the above places?