Some do but not all. It comes from family training. My parents taught me to eat home made everything. My wife was taught the same thing. We taught our kids the same.

If you are taught that supper is a big mac and fries, that is what you know. You most likley will pass that on down to your children.

Now I dunno, but some where along the line, people got lazy and didn't pass good eating down to their kids. Because I doubt there were any fast food joints prior to about 1920 or so. Somebody just got lazy. That is all.