http://en.wikipedia.org/wiki/The_General_Theory_of_Employmen...
We've come a long way since the 1930s, haven't we? Yes, the government can do these things, and -gasp- it works, on a small scale, under certain conditions (economic depression).
The "$500m subsidy" to Tesla costs taxpayers zero after being repaid -- but represents a loan from the median taxpayer of about, oh, I dunno, seventy-five cents.