OK, I understand.
In most states, the only Contractor that is considered the consumer is the General Contractor building a house or a road or something similar. All the subs charge the General Contractor for materials only.
That way, a plumber for example, working for either a General Contractor or a Homeowner, buys a toilet for $150. at his plumbing supply house for wholesale and doesn't pay a sales or use tax. He then charges the General Contractor $165. (for example at a cost + 10% contract), and collects a sales tax based upon the $165., so the state gets the sales tax on an extra $15. rather than if the plumber paid the sales tax to his supplier on the $150.
The next day, the Plumber buys the same toilet to replace a toilet for a homeowner, he charges the homeowner the retail price of the toilet at $250. & collects the sales tax on that; he also charges 250. to install it, so he gets $500. for the job and the state gets the sales tax on an extra $100. than if the Plumber paid it to his supplier.
So, at this point, NC isn't doing it that way & is treating the subcontractors or any contractors doing business with the public the same as General Contractors in my example.
When a General Contract sells a house to a new homeowner, obviously there's no sales tax on the transaction (there are enough other taxes to pay for the homeowner).
Eventually, NC may see the chance to obtain additional revenue and change the rule to the more conventional system that I described and that is in place in many states.
But in the meantime, you are off the hook for the record keeping & aggravation.