Regardless of how you pay for your doctors visits or trips to the emergency room, cash or through taxes you wait for the service, that's the way it is.
The same is true of dentists ( in my experience ), RMTs, Hair cuts, cable service, IT support, furnace repair, etc,etc,etc.
The simple reason is that it is impossible to know exactly how long many of these services will take to perform. Can you imagine you dentist saying "Sorry, you hour is up, I didn't have time to finish maybe you should book a longer appointment next time."
The same is true of MP and SP services, customers are the first ones to complain the girl is a clock watcher if she makes sure your appointment doesn't go over, and many guys quickly accept the extra 10 or 15 mins of an appointment when the girl goes the extra mile to try and give you your money's worth. Well guess what, it does go both ways, a few minutes extra here and there mean that sometimes you are going have an appointment that doesn't start on exactly on time.
I don't like appointments that don't start on time, I always try to be on time. The reality is that people are imperfect and some are down right bad at managing their time. If that is a problem for you as customer you will probably find SPs that don't want to see you. If it's a problem accommodating an SP that may be 10-15 minutes late then you have the choice not go back,. but if you're honest with yourself you'll probably find that you yourself are sometimes late and still get the full time you paid for and whats more you probably often get a little extra.
I don't think more than 10-15 minutes is acceptable, but a little tolerance goes a long way.
T2