Most people don't realize that those massively long freight trains they see crossing the country often have one, or even zero, people onboard.

When I lived in Wisconsin, Wisconsin Central Railroad was lobbying the state to allow it to run trains with only an engineer. It pointed to the safety records of freight trains in New Zealand running with no crew at all as a safety precedent.

I think in the end, it was allowed on routes where the railroad paid to upgrade the grade crossings.