Problem behind this is that you eat a couple here and there, then a couple of this, and a couple of that, and eventually end up going over due to the other trace carbs you didnt know you ate. Almost everything you eat has some trace carbs in it and a lot of us seem to forget that. The 30 grams is an upper limit, but its advised to stay as close to 0 as possible.
That's fair enough, so in the end it really goes to the individual to make sure if they do include portions of fruit, that they actually take count or are avidly aware of the fact that they have less carbs to deal with. Count carbs if you want I guess is a way around it.If you're eating plenty of meat and the occasional berries then shouldn't really be an issue, but as you say Luis if the individual grazes on fruit and other foods that are higher in carbs then you may run into problems.