Where I live you have to wait for a park or you don't get one! I would never dream of glaring or beeping or anything though. If anything I just smile to let them know I'm just waiting till they leave
What annoys me is when they see you waiting, take ages to do what they are doing.... And then don't actually leave!!
Obviously it's fine to do this (and I often do the same if going to more than one store) but its just common courtesy to let the person know that you aren't leaving so they should look for another park.
It's not actually rude to wait for a park. Unless you are blocking other traffic and then it is not on!