There are exceptions but the vast majority of us can accomplish this, we just don't prioritize it. You get what you prioritize.
Survivorship bias is irrelevant
What other factors influence that outside of you making the choice to eat something?
I'm very lucky that the stars aligned, so I don't have to try at all. Really, zero effort.
Others have to try very, very hard every day of their life. They need to think about what they're eating constantly. Do you know when I think about what I'm eating? Never. I just eat whatever I want, whenever I want.
it's a lot easier to prioritize it when you have time, money, and energy. that's my whole point. you are in a position that enables you to manage your weight effectively. many people are not.