The regulatory approval for those is just too expensive in practice. I mean you blow up one star due to cost cutting and nobody trusts the tech ever again...
I love how Carter blows up a star system, and then later McKay blows up 5/6ths of a star system which it turns out is deeply more complicated to pull off.
On the other hand Carter did what she set out to do while McKay fscked up and wasn't trying to blow anything up, so there is also that.
But that was a Joviet power plant with a severe design flaw. They had a foot of up-quark matter at the bottom of their control rods, which increased the reaction rate for a brief moment after the emergency ABSCOND button was pressed. Plus, they were running the reactor at dangerously low graviton flux levels, leading to a pion buildup, during a shift change. Everyone knows those Joviets can't do anything right.
Our Amearthican designs would never have such flaws. They are completely safe, and several are operating around the galaxy already, producing hundreds of exawatts. Unlike the stellar panels recommended by those ill-advised "environmentalists" which can't work in nebula weather, or helioshock plasma turbines that rely on the stellar wind, our plants provide a sustainable base load in all conditions.
The problem was that the science behind those fancy power plants of yours is so complicated, the rest of the galaxy found it easier to just oxidize biomass, and are now scouring every known sector for M-class planets they haven't yet strip-mined from all organic matter.
I say was, because the current problem is that those "environmentalists" you mentioned managed to scare remaining interstellar governments away from this technology, which made them double down on biomass extraction.
On the other hand Carter did what she set out to do while McKay fscked up and wasn't trying to blow anything up, so there is also that.