This is because edacs and LTR use whats called LCN (Logical Channel Numbers). Motorola's format does not.
the radios are programmed with the repeater frequences and their asscociated LCN.. ie the controller tells the radio to "go to LCN3" and the radio goes to whatever frequency is programmed into the channel 3 slot.
moto radios use a math equasion to end up there.. ie "radio, go 25 steps from the base freq". They do this on all bands, the main difference is that on 800 and 900 the base freqs are standardized, VHF/UHF isnt. This is precisely why some radios cannot be used after the 800 rebanding. It is also the same reason why you need additional parameters for programming a VHF/UHF motorola trunking radio.
the advantage to the moto system is new repeaters can be added without having to reprogram the subscriber radios, just the controller. Edacs and LTR would require all the radios to reprogrammed in that case.
