The Fallout world is an anachronistic setting historically divergent from our own, and also is fundamentally different in terms of how science works.
The base concept for the setting is a 1950s World of Tomorrow, decimated by a global atomic war.
This means that before the war, the Fallout world was more or less what the people of the 1950s thought things would be like, a future as envisioned through the lens of the Atomic Age and Jet Age. (See Technological Divergence)
So hovering housecleaning robots and laser guns were the norm, and automobiles looked like Motorama concept vehicles from the 1950s: massive tail-finned and chromed behemoths but with nuclear fusion engines.
Clothing styles and building interiors and furnishings apparently remained very much stuck in the 1950s. Posters and signage are from right out of the 50s. Radio remains the most common mass media, and food products are based on those popularized in the TV dinner era (boxed macaroni and cheese, canned meat, Salisbury steak TV dinners, etc.).
A demonization of communism, which was common during the Second Red Scare of the 1950s, is apparently also a part of everyday life. This is largely due to a massive propaganda campaign launched by the U.S. government during the Resource Wars
The Resource Wars:
- By 2052 natural resources were becoming very scarce. The middle eastern countries which still had plentiful oil raised the prices so high that many small countries went bankrupt, and the European Commonwealth launched a war against the middle east to secure its resources.
- In 2053 a terrorist nuclear weapon destroys the second largest city in Isreal (Tel-Aviv), and a year later there are some nuclear attacks on the middle east, which ramps up fears of a nuclear world war.
- By 2060 the war ends as the middle eastern oil fields run dry and both sides are in ruin.
- In 2066 China invades Alaska to secure the remaining oil, launching a conflict between China and the United States which lasted until January 10 2077, when America reclaims Alaska.
- On October 23, 2077, The Great War is started, and lasted only 2 hours. No one really knows who shot first, but retaliation after retaliation of nuclear missiles left the world a nuclear wasteland
Some of humanity survived The Great War, either by luck, or by being inside VaultTec Vaults or other shelters.