Is it correct to classify fruit juices as added sugar?

If you use a juicer then you are getting just juice with no added sugar. All fruits have natural sugars but there's no way you can change that.  If you prefer orange juice then juice your own oranges rather than buying cartons of it which might not be 'just' juice.  Eating an orange will be far healthier because you'll be eating the fibre also.

Yes.  Fruit juice, even freshly squeezed juice, is mostly sugar.  Most fruits get most of their calories from sugar.  Fruit is delicious but it is NOT a diet food.  

If you are trying to lose weight, you really need to cut out juice.  For example, a "zero added sugar" 100% juice product that uses grape juice as a sweetener has more sugar than a juice cocktail that has some added sugar. 

Other foods you really want to think hard about are processed grains and things like fruit yogurt.  Any carbohydrate turns into sugar in your body.  Any food that has dextrose, fructose, glucose, lactose, maltose, or sucrose has sugar.   Whole grain bread, pasta, and cereal really are not great diet foods.  They increase blood sugar and insulin production and can cause inflammation as well.  

Fruit juice is technically junk food. It's loaded with carbs and sugar. You might as well have a snickers bar for breakfast instead.

not to me....there's no added sugar, just what it has naturally......