There is no way in the world anyone in America could ever starve if they gave one ounce of effort.
Forget foraging in dumpsters. They can eat like a king at Burger King for under $3/day, maybe $1000/year. Plenty of variety--protein, fruits, grain, vegetables...
Half-teasing but half not, seriously.
A vegetarian made a documentary this year to savage fast food (McDonald's specifically). He (and many leftists) would be horrified at your suggestion that they eat at Burger King every day. He ate meat in the film but has since given it up (his girlfriend was vegetarian, don't know if he eats meat again, now).
You are correct. Hot food is cheap.
Then of course there's the Bob Barker method. A stew made from the leftovers of the spay/neuter program. A little garlic, salt pepper and BAM!!!