Answer:
Knocking is like a sign of respect. It is rude to just enter and to simply walk in without announcing your presence first. By knocking on the door before entering the room is simply a sign that u respect the persons privacy.
I always knock on bathroom doors, even if they are slightly ajar, just in case someone is in there and forgot to close or lock the door.
The same applies to bedroom doors, out of respect for the owner of the room’s privacy.
I try to knock in most cases to be polite and show respect of privacy, however I’m not always very consistent and sometimes become complacent, especially with people I am close to such as my family
