Oh, you and I can see the compliance cost as a burden on the economy as a whole. But that isn't what you said.
You said Congress wouldn't make up a bunch of new rules because it would cut into their budget by causing collection to cost too much. The mess we have now is only 'costing' $12B of their budget as far as Congress and 95% of Americans are concerned. If $12B will cover the costs to collect in this convoluted mess, that doesn't seem to be much of a deterrent to additional convoluted rules.
I can just hear Congress debating adding a bunch of new rules to a clean-slate Flat Tax: "Sure we can clarify things a bit here and there. The whole 55,000 pages of clarifications in the old system didn't cost much to implement, these few changes won't cost hardly anything at all !"
Same bad news for the Fair Tax., and I love a cynic - or at least one with an open mind....