The 5G architecture (and LTE for the most part, but 5G was designed ground-up this way) makes very heavy use of remote resources. An actual 5G base station (and most new LTE base stations) is somewhat like an SDR with very little actual protocol logic locally, it connects to a remote controller that handles all of the "business logic." It's an important change because for various reasons, some good and some not so good, the architecture of these networks is really quite complicated and a base station needs a lot of "support services" to function. Making them all remote is basically the change that allowed cell base stations to go from 120sqft concrete huts to the "microcells" we have today where the equipment fits in a pole-mount cabinet.

So the value proposition here is that Amazon is operating the actual network, which is not a small thing. You just have to install the radio hardware.