Our systems weren't more robust, people died, especially children and the elderly and frail, from eating rotten meat, fly blown meat and so on, and that's why people stopped doing it. I had a friend at school, a fit healthy girl who was hospitalised because she went to stay at her Grandmother's and Granny had your views on food.
I absolutely agree about best before dates, and will push use by dates if the produce still seems to me to be fresh, but I like being healthy, not throwing up or putting my health at risk so will happily leave the rotten food to those who want it. As for Bear Grylls, the man is an idiot, why would anyone want to use him as a good example?