Yep, I have scanned as many as 102 channels in the SF Bay Area.The gist of the problem is the quantity of data required to fully cover every channel and sub-channel in the USA.
We here in Lubbock Texas have about 48 channels to keep track of and we are in the median of the pack
Larger cities have even more channels and the information on any one channel can and does change day by day and must be manually collected and/or uploaded by someone somewhere and it is not cheap to maintain such a monster then mesh it with Dish Networks channel guide.