Amount shouldn’t matter in regards to the system, but You have a point there, a person does not incur tax debt unless they’re claiming earnings. And you have to claim enough earnings to actually file for a refund, that can partially or fully “cancel” the meager incentive.

I am/was ignorant on the current state of incentives in S.Korea, if it actually is direct payment, the current system is indeed better than the US system. But without a doubt what their leader proposed is worse.