I guess it’s because of smaller budgets that lunches today are garbage. Back in the day, ours were pretty good. Not 5 star but made by farm mamas with real ingredients. You can’t talk to anyone from my little podunk school who’s eyes don’t go all dreamy remembering the smell of from scratch hot yeast rolls with real butter or giant peanut butter cookies baking wafting through the halls (no one died!). No dried out chicken nuggets for us but lemon pepper chicken with real chicken pieces. No canned fruit cocktail but fresh apple slices with a side of peanut butter and honey or a piece of that fabulous government cheese.
If it’s not the budget, then it’s the too easy access to tvp and prepackaged frozen garbage that’s nuked 5 minutes before the lunch bell.
When I went to school the lunches weren’t that bad (not as good as you describe) but we were kids and it was institutional food. We were picky and the food wasn’t great.
But on Fridays they made pizza and they had to make enough for seconds for nearly everyone. Nothing like pizzeria pizza but we loved it and a second slab of it was only 50 cents or something like that.