I think the point being made is that you shouldn't charge a commercial customer more than a residential customer because, in either case, you have the same amount of experience and training. When you go to a house to service a pc, you still have the training and expertise of your more advanced education. Just knowing the concepts you've learned dealing with servers will influence your troubleshooting tactics and efficiency on a regular PC. So they are benefiting from your experience as well.
You don't forget all of your server work when you go to a residential home do you? No, of course not. It's like the surgeon example you mentioned. Yes he does demand more pay than a regular doctor, but even when he is doing things with a patient that are non surgery related, he still commands the same rate.
Really, with that logic, you can't charge customer's the same.... ever. Because if you went to a job that you had install photoshop or something, you would have to forget your experience with the hardware and most of the other software components. Your not using them, so you shouldn't charge for them. So how much expertise does it take to install Photoshop? You'd make $5 on that job.
My point is, that either your prices are based on your experience or they aren't. You can't separate rates based on what skill set you are more likely to use on that job. All of your experience, skills, and training are intertwined in a technical tapestry, web of wonder, diagnostic directory, knowledge network, or whatever you call it. It's a part of you, your company, your reputation and YOUR PRICE.