Why do I need to sue a defendant in Small Claims court where THEY reside, when they do business in the county where I reside?

This is NC's venue statute:
http://www.ncga.state.nc.us/EnactedLegislation/Statutes/PDF/ByArticle/Chapter_1/Article_7.pdf
The venue statute peculiarly lists the place of "residence" of the corporation as proper venue. If you can prove the company is a foreign corporation, you can sue them where the cause of action occurred.
I am completely unclear as to the wisdom of the statute, other than to say that the statute creates a venue privilege to domestic corporations in NC so that you must sue them where their principal office is. But be that as it may, someone lobbied for a crazy venue privilege statute that favors corporations.
This statute is actually quite to the contrary of most US jurisdictions that plainly make venue the county where the plaintiff resides, except for federal court which has special rules and statutes.
I do note, however, that there may be some federal law that overrides the state statute as to venue privileges.
You could hang your hat on the Fair Debt Collection Practices Act, as a repo guy is a debt collector. And could argue that they tried to collect a debt that was not owed. That would under the FDCPA place venue in your county, since under federal law, the debtor or putative debtor has the venue privilege.
Click on "Find a Lawyer" above and locate a debt collection defense lawyer in your area. There may be more to recover in this case than just a bad repo. And the FDCPA provides attorney's fees to the plaintiff's side. So its worth a shot. Might also result in a remand back to your county.