I think most colleges probably do a good job of this, and the effect of different scales is lessened. I'm not so sure that is the case for scholarships.All I know is that this question was asked of the admission people in almost every session we attended during the campus tours we took and they all talked about using this profile that every HS completes...again they use this to level the playing field.
The bottom line is that they told us that they were looking for students that had challenged themselves (taken the advanced courses and not just the bare minimum), had success (got good grades...As and Bs), and were "involved" in some form or fashion.