I frame it more in terms of like "For each franchise to be average in revenue in each league, what's the cost per fan in the market?" What's the real-world application of that percentage gap you just displayed?
The real world application for $ per person in the market is that you can compare apples to apples across all the markets in the US and see just what to expect for financial health
For example, you sort the list of $ per person among the baseball teams. Well four playoff teams are from the top four markets: SD, NY, LA. How is San Diego paying Tatis, Machado and Bogarts and had Snell and Soto, and Darvish and carrying a payroll that big when they're "small market" ? Well, they only need $78 per person to be league average in revenue. New York teams need $88. Cincinnati, who's kinda sucked forever, needs $263 per person.
The one caveat I'd make to your comment about "a Houston team would have very little penetration" position would be "where's their AHL team?" because that's something that would help.