Comment by RedNifre

The point of it being universal is that you still have a good incentive to work, since every dollar earned is a dollar more in your pocket (initially, before you reach the income level where you need to pay taxes).

Compare that to non-universal social help, where every dollar earned gets subtracted from your social pay, so the first $1000 you earn are effectively taxed 100%, creating an incentive to not start working.