Maybe they are and I’m (partially) justified and maybe I’m attributing malice to stupidity or however that saying goes.
I don’t think they’re trying to trick people into drinking sweet drinks. I think they’re trying to appeal to their largest customer base (calorie conscious buyers). There is limited attention buyers have, so drink makers have to be careful not to put too much, so their most important parts of their message get through. In this case “zero sugar”. They are probably aware that some people like yourself end up with something you don’t like, but they just don’t care because it doesn’t negatively effect enough people for their sales to suffer.
So not really malice, or stupidity on their part, but apathy. They likely know, they just don’t care.