That's the magic of it. You can't just conjure plumbers out of thin air, have some handyman do it, threaten to have your uncle from another state do it, etc, etc, because in order to get your magic piece of paper that says you've done the work the person doing it needs to be licensed by (an agency deputized by) the government and that intentionally takes time to constrain supply.

If this were the government telling everyone to buy landscaping services or something else that's not intentionally supply constrained by the government to benefit incumbent you'd have an argument.