I’m not an expert on the Fallout game canon, but my understanding is that in the alternate universe, the ‘promise’ of atomic energy was embraced post-WWII and the ensuing future by 2077 became the retro-futuristic version of 50s utopic visions of the future. Think an atomic-powered Disneyesque ‘Tomorrowland’ (up until that whole nasty nuclear war business, at least). That’s why you have old-fashioned looking vehicles and TV sets alongside robots. I think @Smapti said it very well in one of the Fallout threads:
Fallout is, at its heart, a dark parody of American exceptionalism. “Absolute dumbass” is exactly the type of wastelander that should flourish in this setting.