People who rush into elevators or onto public transportation when others are trying to get out.

It takes two seconds to see if someone is making their way towards the doors to exit the elevator or exiting trains or cars. You will not be significantly delayed if you wait the extra three seconds for people to leave these spaces, nor will the doors snap you in half if you enter after everyone who needs to get out, gets out. Why are you looking at me and other people like we have two heads when, because you blundered in without looking to see if anyone was coming out, someone slams into you, and moves you? Why do you put the burden of your lack of spatial awareness and social etiquette on everybody fucking-else???