Tips

Question for all of you readers (all like 3 of you, if even!):

Suppose you were to park a car in a restaurant parking lot.  When you leave the restaurant, there is an attendant in the parking lot who works for the restaurant.  Suppose that such attendant hands you the keys to your car and tells you to move it yourself.  You take the keys and go over to your car, intending to move it.  However, your car is blocked in by another car.  The attendant leaves the area.  You ask him if he can move the car that is blocking you in.  He responds that he will not move the other car until you give him a tip.  Suppose that you didn't give him a tip earlier because you were told to move your own car and the person wasn't going to do anything but give you the keys.

Is it proper for the attendant to require a tip before moving the car blocking you in?  Is it proper for any parking attendant to require a tip from any patron?

I'm not the "you" but I'm curious to hear your thoughts.