This page on New Jersey history says:
You might have noticed that in virtually every Turnpike service area, there's a smaller building next to the main building. The smaller is usually closed, even if it has signage for a Carvel or a TCBY. It leads one to wonder: if the structure is never open and there's no business there, why does it exist to begin with?
Hojo, that's why. I've looked at the other locations - there are 12 - and this seems the best bet.
I'll take the old version.