Introducing such a tax would probably require an overhaul of the entire federal tax code, no small order, and something the government last did in 1986. At the time the goal was to simplify the tax system, to raise money more efficiently and with fewer headaches for taxpayers.Ballooned? I don't see any ballooning here: Yes, there is a bit of a jump at the end due to automatic stabilizers and appropriate (though not big enough) countercyclical fiscal policy, but there's clearly no upward trend in federal spending since the mid-1980s. Moreover, federal government purchases - i.e., the stuff that's in the G component of GDP - accounted for 7.5% of GDP in 2008, down from 9.8% in 1986.
Since then, federal spending has ballooned, while the government’s ability to raise taxes has become increasingly inefficient.
Update: Actually, since the graph goes through 2008, the main countercyclical fiscal policy (i.e., the stimulus bill) isn't in there.