[bombcar]

It doesn't really matter on a macro scale if you have social security doing it, or "retirement accounts" doing it - at the base there is capital and value-add (work) and you're transferring from one to the other.

Now perhaps 401ks owning stocks is effectively "lending" capital to the working-class for a fee - but you'd have to argue that.

[triceratops]

It absolutely does matter whether you're taxing wages or capital though.

Wages are constrained by the number of workers. Capital is constrained by total productivity.