In some European countries, which have long required automatic train stop for mainline equipment, historic equipment (such as steam locomotives) is "grandfathered" and can operate as long as there are two crew members in the cab calling signals to each other.

(In most European countries, the practice has long been to have a single engineer alone in the cab.)

See the following account from a steam locomotive cab trip in Austria, the country with which I am most familiar:

http://blog.reynaulds.com/index.php/realities-of-steam-in-winter/

-- Ernest