SWMBO makes wonderful custard.Ever hear of custard? It's close to pudding, both are heated up just enough to thicken, one on the stove top, one in the oven. The mix & serve boxes, you say? Newcomers to the game. Puddings & custards have been made for decades, if not centuries, by using eggs as a thickener which doesn't take effect until 165 degrees F.
As far as the stuff in a TV dinner..... yeah, all bets are off. I grew up on a farm, with farm cooking. Those things I simply never, ever, got at home.