How do you plan to ensure that the people who redeem food coupons are acquiring food for their own consumption, rather than buying it for someone else who will pay them cash for it? The person to whom the coupons are issued would be the person redeeming them, and unless you want to claim that the government owns the food up until the time it's eaten I don't see any basis for saying that the people wouldn't be free to dispose of the food as they see fit.
I agree it will not stop all fraud, however it will reduce greatly the amount of fraud, this is my second choice by the way. My first option would be to Establish Welfare Camps at various Golf Courses or Race Tracks like Santa Anita. 3 hots and a Cot LITERALLY. Allowing for them to come and go to look for work or other “Necessities” only. If you want MY MONEY here are the RULES to receive MY MONEY, if you don’t like it, GET A JOB or STARVE and DIE IN THE STREET.