You seem to have read too quickly, the poster was talking about someone working a cashier in a store that sells bagels, not about someone making money to buy bagels.

Teenagers getting whatever after school jobs they can contribute to incomes for households in poverty. If the McD's kiosk takes the cashier job, the family loses income. I don't want households in poverty. I'm just unconvinced by this mechanism. I'd rather see minimum incomes or policies to deflate housing costs.