ELI5 How did the economy used to function wherein a business could employ more people, and those employees still get a livable wage?

Was watching Back to the Future recently, and when Marty gets to 1955 he sees five people just waiting around at the gas station, springing to action to service any car that pulls up. How was something like that possible without huge wealth inequality between the driver and the workers? How was the owner of the station able to keep that many employed and pay them? I know it’s a throw away visual in an unrealistic movie, but I’ve seen other media with similar tropes. Are they idealising something that never existed? Or does the economy work differently nowadays?