Question: why aren't the sort of nuclear power generators we seem to have no problem strapping on to rockets and shooting into space for our probes scalable for larger projects?
I haven't looked at the numbers, but I expext that while RTGs are simple and reliable, that they aren't cost-competitive with nuclear reactors per unit of energy generated.
From memory, we have actually used them on Earth in a few situations where we need a very long-lasting, albeit very limited in quantity, source of power, like remote, unmanned lighthouses that aren't connected to anything.
Also, I don't believe that, at least with the ones I've read about, one can control their power output. It's just a container of some material that's got enough passive radioactivity to stay warm enough to generate some electricity.