I don't know, but would be willing to bet, that most of these workers were consuming rather more than the equivalent of five cans of beer per day before they started in. The delivery is paced throughout the day so there's no chance any of them get drunk.
By delivering the beer as beer rather than as the cash equivalent encourages pacing things rather than having the workers spend it all on lower cost per unit binge at the end of the day. The FP piece turns pretty snide about the initiative, saying it's enabling alcoholism. Looks a lot more like harm-minimisation to me.