You talk like machines are infallible. They're not. They're designed and programmed by humans after all.
Perfect example of why machines would do a better job at driving. Your comment is typical of humanity at its worst: emotional, quick to judge, irrational, and suffering from both a terrible lack of wisdom and a disturbing amount of over-confidence.
Machines are designed by people, yes, but they aren't granted any negative traits. Nobody will ever design a car which will give a damn if you cut it off, honk at it, or display a political bumper sticker. No program would include random events like a fight with an ex-wife, or "a case of the Mondays". An algorithm will take all relevant data, nothing else, perform calculations to maximize efficiency and safety (including many never-ignored safety measures as mentioned by others above), and execute those with clockwork precision. Not only that but it will do so in direct collaboration with other vehicles using unambiguous communication conveying clear intentions. It will be studied, analyzed, debated, implemented, iterated and improved ad infinitum. It's not about wishy-washy "feeling safe", it's about concrete and measurable improvement.
PS- Traffic isn't safer. Cars are safer. Big difference. Only the machines have improved, while humans have gotten worse.