7-11 has 15 million customers EVERY DAY in Thailand. Nearly a quarter of the population eating at least something from a 7-11 every single day.
The stock of 7-11s is determined by computers tracking what sells. And if you look at what's on the shelves its almost all cheap carbs. Either processed corn or potato snacks or sugary drinks or ready meals that are mostly rice or the toasties that are cheap bread and mayo and ketchup with some cheap processed meat.
When I first came to Thailand in the early 90s Thais added salt to fresh fruit juice drinks. Which was a good idea as most of them worked in the heat. Now, as many have pointed out, Thais commonly add extra sugar to fruit juices.
I also found back then that every Thai, especially every woman, had an encyclopedic knowledge of what plants and herbs were good for nutrients. It wasnt uncommon for Thais to just start gathering leaves if we were stopped somewhere while travelling around as they'd spotted something known to be healthy to eat. I even saw this in a group of university professors, so it wasnt just a rural farmer thing. I'd be surprised if young people today have the same knowledge of nutritional values of traditional and locally available foods.
Thais have always hated walking, even in the early 90s walking more than 50 meters was only done when there were absolutely no other options!`