[techdmn]

There are many parties, generally referred to as "third parties", but there are also many systems working to ensure that only the two parties everyone knows about have any power. First-past-the-post is a big part of the problem, and both parties campaign against alternatives like instant-runoff and ranked-choice voting. The "Big Two" also control televised debates, and have consistently raised requirements for participation in order to exclude other parties. The big parties, big corporations and the big media are all aligned in this, refusing the discuss third parties except in terms of spoilers. People who might vote for a third party are routinely reprimanded for helping the other big party win.

The other option is to try to change a party through the primary process, but the Democratic party in particular has a process very well insulated against public influence. "Super Delegates" (party insiders) until very recently had open and official votes that could easily override a choice by primary voters. In a lawsuit filed after the Democratic Party fought to ensure Hillary Clinton beat Bernie Sanders, a leading member the Democratic Party argued, in court and under oath, the that party was a private organization and had NO OBLIGATION to use any kind of democratic process to chose its nominee. In this last election they didn't even have a primary.

I live in the U.S., I vote, at best I consider it a very flawed, or perhaps well controlled, democracy. In many cases a majority of voters prefer policy changes that are simply off the table for both major parties. Examples are things like winding down the war on drugs, ensuring abortion access, and raising the minimum wage. Neither party will do anything about these issues at the national level, and any progress being made is at the state level - largely in states that have a ballot initiative process where voters can (in some ways) bypass the usual party-controlled political process.