I'm okay with the idea of the overall system being progressive while the individual components are not, but I agree that for political reasons it's safer to keep as many components as possible progressive as well. On the other hand, that gets awfully complicated.
I like the look of Mise's graph in #19.
Dutchfire, I'm not sure "as progressive as possible" means so that everyone comes out nearly equal in the end. I understood it as meaning the curve is smooth, such that there aren't weird jumps and exceptions.
Related.. my governor wants to cut the sales tax by 1% (from 7% to 6%), impose that 6% sales tax on a number of current
exempted categories, and impose a 1% sales tax on a number of other exempted categories. Naturally, opponents are freaking out, saying that the poor, and the economy, will suffer horribly from this. Among the items currently exempted: "Aircraft, including aircraft rental and leasing without pilots, and aircraft parts", and "Nonprescription drugs including medical marijuana". (Guess which is going to 6% and which to 1%.) Some things, like food and prescription drugs, will stay untaxed. Trying to sort this out into separate categories - three now - and determine which will have the most impact on the poor (or, for their purposes, the budget) is just silly.