No one really knows who or what is on these towers. Farmers lease land to some company to construct a tower. Said company builds the tower and then assigns the lease to another company, who furthur assigns it to another company. In most cases, the companies doing the leasing is an LLC named after the property address where the tower is (e.g. 1 Main Street LLC) and it's all washed through a myriad of shell companies.
At that point, you have third party companies that lease and sublet positions on these towers through similarly obfuscated companies to the actual carriers. In other cases, these leasing companies arrays are sitting along side arrays that are owned by the carriers.
Also, you have church steeples, silos, water tanks, and anything else tall that happens to be in the right place for cellular coverage where the owner is happy to take free cash from someone that wants to put antennas on it.
It's not as simple as having VZW's antenna painted bright red and sprint's painted bright yellow and the unpainted one being rogue.