I cannot understand why they don't use two-of-three voting to produce the log entries. It doesn't have to be three machines owned by separate organizations, or

I cannot understand why they don't use two-of-three voting to produce the log entries. It doesn't have to be three machines owned by separate organizations, or even in separate buildings. Just three servers in the same rack, doing the same computations, and nobody signs anything unless one of the other two produces the exact same result.