As far as licensing is concerned, obviously, peculiarlies of state laws would govern.
Havng been in the "collection" side of the biz for a while, I've looked into licensing of collection agencies here in NY State, as I was thinking of going to go into the collection agency business. I finally wound up owning rentals, and there are also similar requirements in requiring a "Real Estate License" to collect rent for others, as I learned after taking some RE licensing courses.
The major thrust of licensing for both professions, here in NY State, is to make sure individuals engaged in it understand the law, and also be bonded. The operative phrase is to "collect for others for a fee". Folks wtih licenses can then get paid in the name of the Collection agency, or the Property Management company, take his or her commission, then remit the remainder to the principals with funds that had to go into escrow accounts.
On the other hand, if the checks are made payable to the company, or the landlord, all the subcontractor or agent has to mail checks in an enclosed envelope, he is merely a courirer, and it is not so clear licenses are required.
I researched all of this when I set up my Real Estate management company, which I didn't call mine a RE maangement company, but a "business service" company to get around the RE licensing requirements. This is even in the case that I'm managing mostly my own properties.
I've been in several companies where independent reps were asked to help collect, and the payment of commssions had in recent years been contignent on the company receiving payment. At no time had any one complained about licensing.
About collecting rents, when I was a small boy, my dad ran a business, in a building with several stores. At one time, the owner asked him to help follow up on rents, and then forward the payments to him, for a small reduction in rent. One neighbor, a retired banker, told my dad it was illegal as collecting rent required a license. Now, after taking the licensing course, the banker may be technically correct.
However, my dad thought it was "looney", did the collections, built a good relation with the ower, who in a few years let my dad buy the property, with good terms. That was back in 1963, he still owns it, now free and clear, and makes over $5,000/month, a nice retirement. Had he listened to the banker, told the guy he needed a license, I doubt things would've turned out so nicely for him.
As to subcontractors, I'm in charge of finances at a "non profit" since I retired from my business, and we hire subcontractors for maintenance, music, dancing and singing. All of them have signed contracts as to the amounts they're paid for the duration of the contract, as well as notice required for termination. I'm responsible for maintaining these contracts.
While I was not privy to the contracts betweem the sales reps and the company when I was with the trading company, those contracte were in fact more elaborate. All of the reps work on the basis of a draw and commissions, and can owe the company substantial sums. One guy owed over $50K, never paid it, when he left, and as I was part of the finance department, I had to go after him.
When I refer to "terminating" subcontractors, I'm referring follwing these contracts.

