If it's a tour run by a corporate enterprise such as the one the one the OP is discussing, the overhead costs are extensive, as they involve office space, utilities, state and federal licensure and permitting, administrative employees, accountants and lawyers and insurance, a vehicle fleet, etc, etc, etc.
I don't believe that's correct. I think this is a one man operation or possibly a very small company. The instructor is the exact same for every tour no matter the location. You'll notice a few of the tours are in Texas, and that instructor lives in Austin. They have changed websites 3 times in the past 3 years (easily found info, I did not dig) and their Facebook page had less than 250 likes as of yesterday.