I am not a fan of Buffett, but this is actually a good proposal. It rewards work.
People who receive EITC are working. They may not have a good job, but depending on the size of their family, they could make $20 or more an hour. This also leaves in place a low minimum wage giving young and low skilled workers more potential employment.
The EITC is a reality. It rewards work it also doesn’t punish success as the amount of money given declines as wages increase, so there is no disincentive to try to make lots more money by working longer and harder.
The EITC may be a reality, but it subsidizes low paying jobs, which could be construed as a form of "corporate welfare" since companies don't have as much incentive to raise wages to retain good workers.
Also, the EITC does punish success since you can work 40 hours and earn x dollars plus the ETIC for weekly wage Y, or you can work 44 hours and earn x+4 dollars plus EITC-4, for the same total of Y dollars. Where's the incentive to work that extra 4 hours?
The "incentive" doesn't really kick in until you earn too much to qualify for EITC.