A couple of hypothetical examples:
* What if one county is dry, but not the other? Does Disney allow purchase/consumption of alcohol on one side of the park, but not the other?
* What if the response time of EMS was significantly different between the two counties (meaning outcomes on one side of the park were far better than the other side)?
* What if the roads on one side are well maintained, but the other side is filled with cracks and potholes (like most city streets), so your initial perception of the park depended on which county you ended up entering the park from?
* What if Disney wants to open a new attraction, but they can't get commitment from the counties to provide the additional power and zoning for it?
How would those things affect your opinion of the park as a guest?