Why Do We Tax Public Employees?

A while back I had a borderline-civil exchange with another blogger over the voting rights of public employees--should they be allowed to vote or do they just have too much at stake?  I can understand the argument that they should not be able to vote but it proves too much: every government contractor, every lobbyist, every beneficiary of a public program, has some kind of stake in government decisions and if we deny them all, then nobody is left.

But it occurs to me that you can turn the point around.  Forget about voting, why do government employees pay taxes?   It's certainly not an impossible idea; we already forgive taxes for soldiers in the combat zone.  No quarrel in principle here, but why not extend it?  Understand, I don't mean to offer them a break here: just net out their salary against their potential tax bill.  If they would have the right to $100 in income with s 30 percent tax rate, then just pay them $70.


I admit that there is something creepily unsettling about the proposition, yet for the life of me I can't think why.  What am I missing?

Afterthought:  It occurs to me that the proposal comes tantalizingly close to a system of corvée.  Maybe that's the point of  the tax exemption for people on active duty: active duty also looks like corvée.