First of all, let’s try to avoid American-bashing, and stay respectful to everyone.
I’ll start: for me it’s the tipping culture. Especially nowadays, with the recent post on !mildlyinfuriating@lemmy.world with the 40% tip, it just seems so weird to me to have to pay extra just so that menu prices can stay low.
I’m not sure voting by default to one party is a consequence of registering with that party. Maybe some psychological effect.
I’d say the main cause is the fact there are only two parties to choose from, so unless you are a moderate (or these days right-moderate) it is just a waste of time looking at candidates and their policies beyond party affiliation.
The related issue is this: in some places in america, the primaries are run by the parties. So you can only vote for canidates (within a party) in the primaries IF you register with that party. In some races the primaries are the important part, because everyone knows which party will win the main election, so who gets the party nomination is basically the undecided part.
I thought there are multiple small parties too?
There are, but first-past-the-post all but guarantees none of them ever win a seat.