> Why did Marx & Engels call for a steeply progressive income tax in the
> Manifesto?
Because only the rich, the very rich and the extremely rich paid income tax in nineteenth century Europe. The Manifesto was written before Marx had arrived at his theory of value, according to which the rich ultimately pay the taxes anyway. After that, Marx did not advocate changes in tax and even criticized those that did in his Critique of the Gotha Program
-- Lew