It may vary state by state, but we don't have to declare a party here.  In primaries, you have to pick one at some point, but that is for obvious reasons.

The whole voter purging stuff is very very very very rare, and has much more to do with the equipment or corruption.  Probably because of 2000, you think that is how it is, but for the VAST MAJORITY of Americans, you register, you get a card and a letter telling you where to vote, and you go vote.  Most Americans who have trouble voting are either non-English speaking or new voters unfamiliar with the process.  Florida wasn't stolen because of people being unable to vote, but because of stealing an election.  I don't see how your system prevents that, given that it is even less transparent than ours.  

Really - I think your registering with your government is basically the same thing as registering to vote, the registering is just done differently.

"Pretending that you already know the answer when you don't is not actually very helpful." ~Migeru.