It seems to be what some sections of GA do best?
The third reason is Hotellings Law ( that's Harold Hotelling the economist) the best place to put your aviation business is next to a competing aviation business. That way you both do better.
That's only if the services provided are essentially similar, and the prices are fixed. H's Law says that if the prices are not fixed, companies will modify them to compete, thus it is in their best interests to be as far apart from each other as possible so they face less competition. There's a reason Coles and Woolies are generally at the opposite ends of the shopping centre from each other, or not co-located at all.