I'm not trying to lose weight, and I've never knowingly bought a specialty orange. Sugar is in basically every plant food, and saying "give up all sugar" means going carnivore plus eggs and a select few dairy products.
Which, to be clear because some people legitimately believe in this diet, this is bad for you. Diets high in animal fat cause heart disease, and eating this much red meat without fiber is going to cause gastrointestinal distress and increase your risk of colon cancer. Also, it is very difficult to eat a reasonable amount of calories when you consume calorically dense food that's high in fat.
It's a matter of amount of course. A tomato has 1/4th the sugar of a normal orange.
The point here is saying "fruit is healthy" is just not true in any sort of black and white sense. Someone can easily get fat and be unhealthy by eating fruits with lots of sugar, and if they are juicing them, even more so.