The Chevy Vega was designed in conjunction with those rail cars. The supply chain folks at GM realized that they could make the car even less expensive if they could get more cars in a rail car.
So, the design of the Vega had to be compatible with shipping vertically. Rail cars had to be specially designed and manufactured for the Vega.
The vast majority of the non-Vega cars at this time were delivered by standard rail cars though.
If you are looking for a car to be delivered to you normally, on all 4 wheels, then drop by Ron Westphal Chevrolet in Aurora, IL. We only delivery cars right-side up. LOL!