It’s real life too. I never understood it either but as an adult I’ve met too many people who really are that wasteful.

Maybe it’s all based on water availability where you grew up, or frugality of your household. I’ve met people who run water while shaving, I do so only to rinse the blade and my face, while my grandparents in a rural area where shocked that you wouldn’t limit it to a cup to swish your blade