It's a question of balance with "Street Beggars". Your point is valid re 7th cheese sarnie but Joe public is equally reluctant to feed an alcohol/tobacco/drug habit ("alcohol effect") by giving cash.

There have been various voucher schemes around to bridge the two perspectives, but not sure how successful they have been. Vouchers always seem to stigmatise people, despite being a logical solution. Then retailers still allow beer or biftas to be bought with food vouchers, preferring the trade over exercising moral judgements.

Then there is the "cute dog" effect. For years there was a street beggar at London Bridge Station who had an appealing Heinz dog as companion. He always had piles of dog food, but little given for himself, no doubt due to the "alcohol effect" above