Intermodal shipping containers are arguable the most significant technology of the 20th century. They did more to improve worldwide standard of living, than any other advancement. Including medical.
A surprisingly huge leap forward for the world was air conditioning. Singapore's founding father, Lee Kuan Yew, said it was essential for his country's development. Without AC a huge swath of the world would still be seen by the West as this uninhabitable, uncivilized jungle.