It's not just looks and height that should be taxed. So too should having meat and two veg, according to this paper (pdf, via CEPR).
The thinking here is based on an old, well-established theory - Frank Ramsey's "inverse elasticity" rule. This says that taxes should be lightest on those goods which are most price elastic. And women's labour supply is more price-elastic than men's. Men will go out to work (or not) more or less come what may. But some women, at the margin, can choose between being a home-maker or going out to work. This choice means their labour supply is more responsive to tax rates than men's. Which in turn means that shifting tax from women to men might raise labour supply and hence output.
But that's not all. If women go out to work more, men will have to share the housework and childcare more. Is this efficient?
If you believe in diminishing returns, yes. The first hour a man spends looking after the kids should be better quality than the 50th hour a frazzled mum spends with them.
But this isn't necessarily so. Some men might be so bad at childcare that children are better off with their mother. In such cases, incentives for women to go out to work would backfire.
All this raises the question. If there is, in theory, something to be said for taxing height, gender, or looks, why does the government never even consider these possibilities? It can't be because such schemes are complicated; the existence of the tax credit system shows the government doesn't value simplicity highly. Could it be that the government taxes income for the same reason Willie Sutton robbed banks - because that's where the money is?