Corporate office can set whatever policy they want, just like Costco and Sam's Club can choose to only sell to members, and they can further limit membership by restrictive conditions, such as you must hold (this and that license), be a student of (this and that school), residents of (whatever area), but I don't believe in further .gov involvement in restricting procurement route for the sake of protecting trades. We're not talking about DEA scheduled or EPA controlled substances.
Do you believe in restricting the sale of motor oil to EPA certified business accounts only to curb illegal disposal and perhaps requiring permits to make repairs to any automobiles registered to operate on public right of way to ensure profitability for the trades?
It's no worse than no self-pump law in Oregon and New Jersey.
HVAC industry likes to restrict parts and equipment supply chain, because of demand by contractors and the manufacture's desire to attract installing contractors, because they know that restricting supply is often effective in causing people to have to call service. So, you can't buy a new condenser fan motor and supply house won't sell it to you when its really not that much more complicated than replacing a radiator fan motor on a car.
Before, you had one option. Call for service.
Now, you have more choice.
1. Order it online and wait a few days without AC
2. Call for service
If its blazing hot, people tend to fall for #2.