voting "machines" eliminate voting

I think it has to do with the differences in states levels of control in Canada and the US..
plus the differences between parliamentary governments and the US 'style'. Each US state can
set its own election rules on who deals with the election materials. The Federal government
can really only give outlines and say that if you 'fail' to meet those standards you lose
federal funding. The states are really protective of this, as it is one of the last
'sovereign' powers they have in comparison to the Federal government. 

However, I will admit that I am on a thin branch here.. and could be quite wrong.