I know a thing or two about legitimate dumpster diving. It's not a new thing. Movements have been born and died based on it. Hippies, Freegans, urban-reclamationists, have all dove into dumpsters to get food since the 60s. If you know where to go, you can make out ok. You don't go to some random dumpster by an apartment complex. You go to a restaurant or supermarket, at the right time, just as 'recently expired' goods are being tossed. Supermarkets do throw out hundreds of pounds of perfectly edible but past sell by date produce and packaged products. It's stuff that would legitimately be fair game in a restaurant, or something that a soup kitchen would be grateful for, but it gets tossed out because it isn't prime commercial commodity.
In a perfect world, stuff like this would be processed, and donated to needy people, but since this is all about commerce and making money, and fear of negative public image, or that someone might possibly get sick and sue, food businesses throw away tons of safe and edible good daily. It's a fact. There were some programs set up to allow stores to donate things like this, but many stores refuse to, over liability and insurance issues. So, you have savvy homeless and adventurous types who go to restaurants, grocery stores and the like to get free foods. Yes it's kind of gross, you may encounter some gamey and overripe smells, but lots of that stuff is salvageable and perfectly fine.
That said, having so extreme an aversion or advocacy for this that you come to insulting arguments is not worth it. People do it. It's a thing. Not your thing? Ok then. It's over.