Do the places you are referring to not require heat? If so I don't see why having a separate heating and cooling system would be cheaper to maintain than a single system. Come to think of it I don't see why a heatpump would be more expensive to maintain than split AC. I guess there is some extra circuitry to make sure it doesn't ice up in the winter and maybe backup resistance heating builtin.

That's the same thing, no?

Why would it be easier to install/maintain? It's basically the same machine.

Split units are heat pumps right? They heat and cool. What’s the catch? They don’t have a very high range of operation?