why was an MD not sent?

From the text:

"Neither of you is an M.D. Why didn't they send an M.D. from Emergency?"

"Hell! " the operator's cigarette moved on his lips. "We get these cases nine or ten a night. Got so many, starting a few years ago, we had the special machines built. With the optical lens, of course, that was new; the rest is ancient. You don't need an M.D., case like this; all you need is two handymen, clean up the problem in half an hour."