It's a choice, not a census

I have overheard snippets of conversations in the last few weeks that can only mean one thing: there are people (not an insignificant amount) that do not know they can vote for anyone even if they are registered for a different part.
Although this was shocking at first, the more I think about it, the more it makes sense that people might think that.
If you are registered in some party and have voted that ticket election after election, especially somewhere that has that convenient All My Party button/lever, you might start thinking that it is not a choice but an instruction.
Democracy!