A sub-trope of Anachronism Stew
. The cultural snapshot we have of trains, especially as portrayed in children's literature, seems frozen in time. Sister and Brother Berenstain may eat too much modern junk food, watch too much TV and do their homework on a computer, but when the time comes to take the train to visit Aunt Tilly, suddenly it's 1899 all over again. The Grizzly Express comes complete with steam engine, caboose, coal car, coal tender, dining car and conductors snapping their hole punches.
Thomas the Tank Engine and Chuggington continue the strange cultural confusion.
This trope was more general through the early 1980's. Movies and TV shows might still portray steam trains in exotic foreign locales, but as the 20th century wound down, Steam Never Dies retreated to children's literature and cartoons, where it seems permanently entrenched.