If you haven't already, look at the satellite view of the location of the Town Pump in Sidney, follow the power lines that run along the edge of the shop building, as seen in the father's video/interview. I didn't find a more recent view that would show the actual Town Pump buildings, the fences, the extending addition on the shop, and the stairs leading to the apartment. If Katelynn was using the back gate and, not driving, it could be that no one on the same street ever saw her comings and goings.
The father said that one neighbor had some video that didn't show anything. He did not say there was a tenant in the other apartment and it seemed to me that the reporter may have known that as he did not ask about a tenant when he commented that there was a "lower apartment". He also didn't ask if the cars were a tenants', he only asked if any car was Katelynn's. Since the father drives and works on modified dirt track racing cars, I would expect there to be lots of vehicles around his shop.