Consistent Scroll Bars in every Program designed for Unity

There are two types of scroll bar in the actual version of Unity:
The first one is the "classic" scroll bar, like in Firefox, Thunderbird, LibreOffice, … This one is used most. (Screenshot: http://ubuntuone.com/3UG5BUXJzj9Qj736wrlXse)
The first second is with the small orange line. It's used in the Ubuntu Update Manager, Eclipse, Terminal, Evince, … That one is specific for Unity. (Screenshot: http://ubuntuone.com/6znKrOr7JDaNQrjLB6Kj1z)

Why can't there be only one type of scroll bar? Why should there be two?
I propose the orange Unity scroll bar for every program. The desktop would look cleaner, websides would be wider, the design would be more innovative …
For example, Firefox could looks like this with the Unity scroll bar: (Screenshot: http://ubuntuone.com/6UfjDC9cIrk27YBOCferVK)