They shot John, Bobby, Martin, and Malcolm. They probably would have shot Bernie too if he won the primary.

First past the post voting systems make sure there are only two parties and two candidates. A third party doesn't stand a chance.

Of course neither party wants to change things because it works for them.

Overthrowing the whole broken system is also an alternative. The sheeple are too comfortable with their neolib and fascist overlords though.

It's the voting system

In a word: corruption.

Also: Bo Burnham is equally baffled and wrote a short banger about it