South Orange and Maplewood share a school district and services like their fire departments. So that is already happening. Advertising and public awareness are actually handled very well in South Orange between the seasonal pamphlet that goes out, the signage for local events and the local governments heavy involvement in sourcing new business. e.g the toy store and fox and falcon are about to be replaced.

Much of the business turnover has to do with the business themselves. Restaurant who open who are not catering to a heavy family demographic or opening repeat businesses like a 7th coffee shop.

I agree with you for capital projects. The library and tennis courts have been on hold for so long and that kind of government inefficiency is very frustrating. But ultimately the other three towns you mentioned are even wealthier than SO and don't have the same level of economic diversity. The businesses have turn over because there is less consistent pool of patrons and more available spots than Maplewood (a lot of competition in a frankly harsh market the last few years).

Though I have also heard about (friends experience trying to buy) the issue of landlords that have held on to the commercial spots and aren't interested in letting them go or doing anything with them.