The grading system here in Scotland is not backwards. In primary school (the first seven years) plus the first two of secondary (ie. high school) you progress a bunch of general grades like reading, writing etc. from A to E, or F in exceptional cases. Nothing is graded A to F, it is just a cumulative record of your skills that is assessed annually.
And then the next two years of secondary use a numbering system, 1-7 for grades, but again the marking is still slightly different and classes are organised into groups (credit (1-2), general(3-4), foundation(5-6)). Then the last two years (non-compulsary) it's a pretty similar grading system to the US; A-C, D and then F, with A being the highest.
It's really quite simple.