Well, actually, a very big difference. Primaries are "free" for voters, but they are hardly free for the contestants. In addition to which, in the US, actually getting the central party blessing requires a combination of money-generating prowess and ass-kissing, toe the corporate line behavior, demonstrated over a significant period of time. US federal candidates, if they want to stand a chance, bascially have to take a catamite aptitude test, pass it, then hope no one else passed it better.

What's more, this is just the PS internal selection. Nothing stops a candidate from the PS to present himself in the presidential even if they lose here, there's been especially worries about Fabius in this regard. And running as an independent (ie non PS, UMP or a la limite the PCF, the Greens or the UDF) of modest means in France does not mean you are consigned to the dustbin of electoral hopes. Speaking for the left, in the first round in '02, the PS standard bearer got 16% of the vote, PCF and Greens another 7 or 8, and left splinters (Laguiller, Chevenement, et c) got actually like 20%. And that vote, the "real" left primary, was indeed free.

Additionally, you don't have to be a millionaire to get into the Senate in France, though it doesn't necessarily hurt. In the US, being a regular guy, as opposed to wealthy, is the exception, not the rule at nearly all levels of Federal politics.

Unsurprisingly no one has represented the poor in the US since roughly 1968.

Fai de bèn a Bertrand, te lou rendra en cagant

Now seriously, can you explain the difference between

• registered Democrat voter
  
• Democrat donor
  
• Democrat activist/volunteer
  
• Democratic Party "member" (card-carrying?)
  
• What is the DLC?

If you want the Socialist [or any other] Party candidate to represent you, you join the party [which may or may not include paying dues]. If none of the parties' candidates represents you, you can form your own party.

Those whom the Gods wish to destroy They first make mad. -- Euripides