Holding the door for strangers?

𝑔𝒶
Another post made me think about this. How do you feel about holding the door to a store, restaurant, etc for strangers when they are walking behind you? Do you do it? Do you say thank you if someone else does it for you? 
It infuriates me (exaggeration) when others don't do this or don't say thank you if someone else does. It's a basic manner that everyone should have in my opinion. It's not that hard and it doesn't take much time out of your day to be kind to someone else. 
What are some other basic manners some people lack that annoy you?