Does the word appointment mean anything to Doctors and Dentists?

Every year or so, I have to make a trip to see my dentist and my doctor. Invariably, I make an appointment before I go. But that appointment really doesn't mean anything to the doctor's office. Let's say I make an appointment at 3PM, I will be extremely lucky if I get to see the doctor within half an hour, before 3.30PM. More often than I like, it's almost always an hour later or even 2 hours later than the actual appointment time. Doctor's office doesn't understand the concept of appointment at all. Or they simply don't care. Why is it so hard to make sensible appointment? If you can't fit me in at 3PM, just let me know, I will come some other time. My time is important to me too. I kind of like my doctor and dentist. Except the waiting part, in their office, with other patients, flipping old magazines.