This is just completely false. People always use this as an excuse but it's simply not true.
You can find chicken for $1/lb, or chicken breasts for like $2/lb, or pork chops for like $3/lb if you look for it. Then you can buy frozen veggies and make a very healthy and tasty meal in about 10-15 minutes of effort.
The problem though is that takes effort. People would rather drive for 15 minutes round trip to get Wendy's than spend 15 minutes in the kitchen.
IMO what it all boils down is nothing but pure laziness. Everything else in between is just an excuse that could be summed up to laziness. And even though I eat fairly healthy and workout regularly, I still get lazy at times myself so I get it, but I'm not making an excuse at those times, I know it's me being lazy.