Why else would you need so many different frequency bands, to use multiple channels ("a limited number") among them at once, and to change channels to avoid interference? This is almost certainly intended for drone control and telemetry. Of course, they could buy an off-the-shelf solution, but it would look like a whole bunch of little boxes connected by wires, and it would introduce many potential points of failure. They need to logically have a separate radio module for each RX, because the 3-in-1 or 4-in-1 radio modules which can be used to implement multiple protocols only let you activate one radio module at a time. You might be able to switch between them rapidly enough to send messages with lots of different protocols, I don't know about that, but receiving is a different story.
Background for the uninitiated follows: As it is, right now you can buy a diversity receiver off the shelf, and plug multiple receivers into it. Although this is normally used to use multiple receivers which are all receiving the same signal, simply to get more antennas receiving it to mitigate orientation and blocking issues, there's no reason why it couldn't be different signals even with an off-the-shelf diversity RX as long as your replacements still spoke the same serial protocol. Then you'd put multiple transmit modules into your TX, probably connected to the PPM output if again this is all off-the-shelf, and then you'd bind each RX to a different TX module. In this way you could have e.g. 900 MHz and 2.4 GHz at the same time, and if one band dropped out, the RX would use the other automagically.
What else could Amazon possibly be doing with this? It's not for providing people with internet access.