I think you hit on one important distinction. Although summits with roads are acceptable SOTA does not allow operation from a vehicle or anyway connected to a vehicle to count as a valid activation. The equipment must be carried by the activating team but how far is not defined.
Power must be stand-alone battery, solar or similar. No fossil fuels and no fixed source.
I don't think anyone means to be exclusive but I believe the spirit of SOTA is activate summits that would otherwise be relatively difficult and unusual. Putting Mt. Evans or Pikes Peak isn't a huge challenge. I think walking across a parking lot is not sufficient to count, it would have to be a legitimate hike from a trailhead, but that's just my opinion.
Probably should get in touch with Steve, WG0AT, about it, too.