In vanilla, there is all that mention of people liking to work for Synth over Rheinland groups because they actually get paid. That's especially true with the BHG.
Synth has also purchased almost 90% of the planet and has been engaged in a massive environmental modification program for at least 50 years, possibly more, but I'd have to check that part. It would take quite a while to fix the environment enough to support the Rheinland population, not to mention Rheinland essentially having to take the cost of the 80 Years War again.
It's really hard to figure the discussion, however, as Rheinland had crippling unemployment and inflation in vanilla and seems to be ok by Disco.
Also, all that stuff that just got posted by Slavik.
However, Rheinland could still theoretically get out of it by selling themselves to Kusari instead of Liberty now. Until the next conflict, as they'd just be digging themselves deeper and deeper.