bill writes:

"Protecting the consumer" and "raising standards of professionalism" is
precisely why we have licensing.

No, those things are perfectly well achieved with voluntary standards that
intelligent people can pay for if they choose.

When the government forbids, ultimately with threats of force, a willing
buyer and willing seller to exchange in an honest transaction, because of a
lack of a trade license, then that has nothing to do with consumer
protection or professionalism. It is motivated by greed, of the tradesman
who benefits from higher prices and less competition, and of the politician
who gains a moneyed special interest.

In the extreme, the government itself will decide who will do the work and
tax us to pay for it, like the public schools.