> Even doing independent contracting on the side seems like a minefield w.r.t. quarterly tax payments, estimated tax, etc.. in the US at least. I'm sure I could figure it out but just earning income for some side work seems like a liability and a big headache.

It's really not hard -- it takes maybe 15 minutes per year, and if you own any stocks outside a 401k, you probably already need to make quarterly estimated payments. If it's too much trouble, you can just hire an accountant to take care of it for you. At any rate, it shouldn't be a significant obstacle to contracting.