J R,
Doing a search of the site I don't see 72 Mhz mentioned except for reciever frequecies. Although some transmitters state that other frequencies are available on request. From this I get the impression this is to support older systems. I know many industrial radio control systems were switched to a higher band when the R/C narrow band came out. Though they were not specifically on our band I think some of them were wide band. I don't know for sure if wide band industrial controllers are still legal or not.

Mr. Matt
I think that 72.39 is channel 30? If so you may have to share that frequency with me if you and I show up at the same site. If an industrial control station is given a license, I think it will be the only user of that frequency withen a certain radius, don't know what radius the FCC uses. Any one else using that frequency withen that radius would be illegal. Though they may have provisions for shared use of licensed frequencies also.