Cars were originally assembled in an assembly line by men working in the automotive industry. This was a pretty slow process and few were produced. In 1900, there were only about 4,000 passenger cars produced in the US.
When artificial intelligence was invented, machines were able to mass-produce cars.
Cars are now produced very fast, are safer, more reliable, and last for a longer amount of time. In 2018, there were almost 11 million cars produced in the United States.