In a previous article, "Private" said:
Being a Canadian, I am also a big fan of the Roberson square screw and think
they are superior to the Phillips in every way. IIRC there is some real
historical chauvinism that resulted in the use of the Phillips design in the
USA and the rejection of the superior Robertson.

Look at the Wikipedia article
http://en.wikipedia.org/wiki/Robertson_screwdriver
According to it, Henry Ford wanted to use Robertson screws on Fords, but
Robertson had been screwed (sorry) by a previous licensee and refused to
license any other screw manufacturer to make them. Ford decided that he
wouldn't trust a single sourced screw, so went to something else. And
thus, Robertson missed his chance to have Robertson screws become very
common in the US.

--
Paul Tomblin http://blog.xcski.com/
"They that can give up essential liberty to obtain a little temporary
safety deserve neither liberty nor safety" - Ben Franklin