Not quite. The plumber and electrician are necessary for the existence of the city. The DMV clerk is needed only for the enforcement of a licensing scheme - if his office shut down completely the city would go on functioning with little or no change.
There would need to be some sort of alternate mechanism for ensuring that people learn to drive a car safely before driving a car. Presumably that mechanism would involve some replacement job for the former DMV clerk.
Once again, here's the new thread for posting quotes, with the usual rules:
Please post all quotes separately, so that they can be voted up/down separately. (If they are strongly related, reply to your own comments. If strongly ordered, then go ahead and post them together.)