At the risk of going off-topic, I find "Doctors" to be almost as arrogant as engineers.

I remember one day at the parts house, where a dozen of us sttod idly by, as a man tied up the counter guy. He didn't know what he wanted, or how to do things... but ever other statement referred to his job as a 'doctor.' I really wanted to grab him by the scruff, and show him the 'wholesale only' sign at the entrance. I waited in vain for the clerk to ask him if he had a 'prescription' from his 'primary care maintenance professional,' or to hand him 15 pages of paperwork.

Otherwise, it seems that "Doctors" here are the class most likely to hire idlers along the river to do their work under their 'homeowner' permits. They simply can't bear the thought of paying more than $8/hr! Which is interesting, because it was the medical profession that showd us all the way to institute licensing. Every "doctor" I've met has been quite able to detail all the sundry expenses that make that office visit a $90 experience. Do they think they live in an alternative universe?

Ultimately, though, "Why do you charge so much?" is a fair question. There are essentially three basic reasons:
1) The costs associated with running a business;
2) The costs associated with your being readily available; and,
3) That they are paying for your training, experience, and judgement as well.

As for comparisons, well .... all are free to look at my truck, look at my home, and compare them to theirs ... then decide who needs to subsidize the other!