I think it's more or less just the US that taxes its citizens when they live and work overseas.

I can see the argument for maybe a "contribution" of 1-5% to cover the services you keep on using (diplomatic) and some of the costs you already incurred (education, whatever you used before you left), but anything above that seems a bit unreasonable, imvho (and I'm quite supportive of high/progressive/redistributive taxes generally).