A lot of cars, once they get older, will encounter some form of rust at some point. While quite normal, the type of rust you're seeing could be detrimental to your safety and the structural rigidity of the car in question. Surface rust is relatively harmless and easy to fix, so removing this while you're able to could prevent the surface rust from going any deeper. Meanwhile, scale rust would be tougher to remove, but it's still not serious if you treat it in time. On the other hand, penetrating rust is serious, especially when the penetrating rust is so bad, that holes are formed due to metal flaking away. At that point, it's far too much rust to be easily fixable.