Yeah, there's the same issue with "hot water heaters" in the US. It's still a big tank that it keeps hot all the time, and it's by far the most commonplace hot water system. On-demand heaters are becoming available, to the point where it's an obvious consideration, but most people (myself included) are too lazy to replace a working unit.

Also, there are electronically controlled valves specifically designed for radiator systems, which would help prevent heat wastage from pipes to unused radiators.