And let's not forget the necessary infrastructure to get and store bulk frozen food, plus the time, infrastructure, and supplies needed to prepare it. How many 6-pound bags of broccoli can you manage while changing buses? How many fit in the freezer of the small, old fridge your apartment has? How long can you spend cooking when you're pulling hours at two different low-wage jobs with erratic schedules and still have to get the kids to school?

I cook and eat a lot of healthy stuff, and I do it at a pretty reasonable price. But it is definitely a luxury that I pay for in time, and it still only works because I have decent infrastructure.

For those who did not grow up poor, it's worth reading John Scalzi's "Being Poor" to get a feel for the experience: http://whatever.scalzi.com/2005/09/03/being-poor/