That's interesting. Here in the States they use heat pumps in a similar fashion, except it's backed by heating coils (electric furnace). As you say, the heat pump is much more efficient - until it isn't. Then the system switches over to heating coils.
Where we have natural gas available we tend to just install a gas furnace and leave it at that.
It depends. In my 2016 build, my heat/cooling is heat pump, my hot water is gas (so is my stove). But I’m in Seattle where heat pumps don’t need a backup, and electricity is fairly cheap. A gas furnace would seem like a waste even though we have a gas line, although we do have a gas fireplace that we use for heat more often than the heat pump (which we only use when it is really cold).
Where we have natural gas available we tend to just install a gas furnace and leave it at that.