@engineer,
I'm not a doctor (but I can play one from time to time)...I believe the reason, doctors/lawyers, etc get paid so much per hour is the time, cost of the additional education and experience and knowledge. Think about the time spent to obtain a medical degree, not to mention the expense of this degree.
He probably complains -- because it would make more sense to stay in his office and get compensated higher. In other words, if you could be in your office -- not travel where ever he has to travel and get $1,000, why would he travel and get $500?