Regarding MURS radios working with Walmart* radios…yes they do. I am not surprised some people out there want to troll Walmart* employees on MURS.
IIRC, the factory default codeplug in the Motorola RMM series MURS radios is the codedplug used in the MURS portable that Motorola sells exclusively to Walmart*. I suspect the Walmart* codeplug became the factory default codeplug for the RMM series because Walmart* buys so many of them. I think Walmart* was using 154.57 and 154.6MHz long before MURS was created and it made sense to stay there.