The pro-payment crowd assumes the main barrier to vaccination is cost. It isn't. Most unvaccinated adults already get free shots, so a cash reward targets the wrong problem. Worse, paying people can backfire by crowding out intrinsic motivation. Studies on blood donation and other prosocial behaviors show that introducing money often reduces participation once the payment disappears, and it can make people more suspicious of the vaccine itself. If payment were the fix, we would have seen it work by now. It doesn't address hesitancy, misinformation, or distrust. It just spends money to nudge people who likely weren't the holdouts anyway.