This is not necessarily correct. As mentioned previously, some coaches have that capability and some don't.
My previous coach (2008 Safari Simba RD) was a very close cousin of your Knight (maybe even a half-sister) and even though the owner's manual stipulated that my chassis batteries would be charged from shore power......it did not. I had to call Monaco Tech to find out for sure.
So, I purchased a Battery Minder and while that worked just fine, I got tired of having to run an extension cord from the engine heat 120v outlet on the driver's side to the battery compartment on the passenger side. At the advice of others here, I purchased and installed an Trik-L-Start. Three small wires and no 120vac required. No more dead chassis batteries and no further input from me everytime we stopped for the night.
So yes, your situation is normal. Get a Trik-l-start and it will solve your problem.