I really don't think everyone knows this at all. The number of parents I know who really genuinely believe "no added sugar" means healthy and good for their DC I find astounding. Also cafes, soft play centres, kids' parties will all push no added sugar drinks, puddings etc at you.
When what it really means is that either they have used a concentrated fruit sugar product instead, like concentrated apple juice - basically sugar - to get around the rules so they don't have to call it "added sugar" – or they have added artificial sweeteners, which may or may not have adverse effects but which also confuse your body because you are not getting the calories your body expects from the sweetness, and also encourage people to think "Hey I am having "healthy" squash so I can have 5 pieces of chocolate cake and loads of crisps".
I have always avoided "no added sugar" products mainly because some of the artificial sweeteners used seem to give me skin rashes, though now also for the other reasons. And it is so hard to find the products I want. Things like medicine, squash, yoghurt often come only on the "no added sugar" variety, as default.
Same for "low-fat" products which often means lots of unnecessary sugar and lots of weird bulking ingredients which are not nutritious like real food. Yet people lap them up.
There should really be a major education programme and law overhaul so that manufacturers are not allowed to fool people like this.
I and my family don't have a perfect, glowing-with-health diet, there are some sweet snacks and shortcuts in there, but basically we follow the same idea of cooking from scratch, raw ingredients, unprocessed stuff as far as possible. My DC have sweets and puddings sometimes but NOT the low-fat/no added sugar stuff. I also try to teach them about what various foods do for your body, encourage them to self-moderate etc, and get exercise. They are slim, and while I wouldn't mind a more toned post-pregnancy stomach, me and DP are healthy weights. So you don't need all this low-fat, no-sugar crap to avoid being fat.
Yet, a lot of people buy this stuff, and a lot of people are fat.