The family thinks this child needs extra milk to make up for the lost amount. Another family is sure that the weight charts were rigged because one of the doctors on the panel happened to have a fat baby. They think the amount their smaller baby is receiving is too small. Someone else doesn't like their neighbor, and maliciously spreads a false rumor that they have bribed the clerks to increase their ration of milk and decrease someone else's so the books still balance. It gets worse.
Someone actually does bribe the clerks to increase the milk ration for their baby.
Even so, they are beginning on the path to a society that runs on bribes and backdoor deals, as the Soviet Union did. Having once taken a harmless bribe, the clerk has, without knowing or intending to, reduced his own reluctance to take bribes. What's more, the clerk has the problem now, of enjoying the fruits of the bribe. Everyone knows that he has only what he needs, just like everyone else. If he buys something extravagant, people will see and know that he took a bribe.