It's unfair to make a charging station exclusive only to one vehicle marque.
Imagine if from the start of horseless carriages, Ford cars could only refuel at Ford stations, GM cars could only refuel at GM stations, Packard cars at Packard stations, BMW cars at BMW stations, and so on and on.
A family on a road-trip in the olden days might pass by a GM station, but the nearest Ford station for their 1933 Ford V8 would be more miles away than the range they have left on their fuel tank!
Then imagine a family who has a Packard! Packard and Studebaker makes a merge (albeit ill-fated) so suppose all Packard and Studebaker stations are refitted to take both makes of vehicles.
Then in the 1960s, Packard-Studebaker goes belly-up. That means their gas stations go belly-up, too, right?
WHERE WOULD THAT LEAD THE MOTORISTS DRIVING DEFUNCT CAR MAKES?
If, Heaven Forbid, Tesla somehow goes under, what happens to their charging network? HOW WOULD TESLA OWNERS CHARGE AFTERWARDS?
The most obvious barrier was that Ford (or any other marque) didn't own the gasoline, nor did they have a guaranteed access to it. Standard Oil (and its derivatives after it was broken up in 1913) were powerful companies, which weren't about to give up control of direct gasoline sales (I'm not even sure if the supreme court would have allowed an auto company to own a gas station chain, for fear of a vertical monopoly).