They already do. I got paid more then Legs...... I also got more money for the high risk activities that I did. There is Pro Pay, Special duty pay and a whole bunch of other pays.
Here is a better example:
O4 Armor officer with 8 years in makes
MUCH less then a O4 Neurosurgeon with 8 year in. Same rank, same time in...... But jobs are much different and the pay reflects that.
Same would go for a E7 68W with 12 years in the 1CAV vs a E7 68W with 12 years in that is in JSOC.
Do a lot more work and you get paid a lot more...... Well
REAL Work.
Of course this does not take into account all of the time that the CAV Medic spends doing police call or cutting the grass. How can you put a price on that?