small shop can make a car. When a small shop makes a car, amortizing the R&D cost means that car has a sticker price of $250,000. It actually does not cost Ferrari 10x more to actually manufacture a car than it costs Chevrolet, but it costs them every bit as much, if not more, to design the car and its fabrication process.
1. Ferrari is not a small shop. It's fucking huge actually.
2. I'm positively sure you have it backwards, RnD is cheap for a small shop. A single smart guy could knock most of important stuff out in a week or less according to a vision in his mind, and later on they do improvements and adjustments while on production. While companies like Ford or General Motors spend hundreds of millions first researching what people buy and what what earns how much and what costs how much so on and so on, then they pay some art school hack to scribble some lines on a drawing board, and then that's the concept, then they spend tens of millions turning that drawing into a non functional shell called a "Concept car", then they spend millions to present that at some fancy car show like Tokyo Auto Salon, then they spend millions hyping it in the press. And only then does the development of the actual production car start, which then takes likes 5-10 years and costs additional hundreds of millions, because they for one are designed by committees with no passion or vision of what they are making and who go back and forth endlessly bickering with each other over shit that doesn't matter, and interrupt the engineers work. And two, they can't just make improvement while on production, cause that requires new machines that cost millions, and doing recalls is bad publicity. so TLDR, a decade of work, and hundreds of millions.
But now we get to production, A small shop doesn't have a automated production line that can assemble a car in a matter of hours, instead they have to do everything by hand, which totals up to many thousands of work hours per car, all of which you have to include in the price to make a profit. In addition, the large manufacturers buy in bulk and get hefty discounts on raw materials, compared to the plebs.
Henry ford didn't drive all the stagecoach builders to bankruptcy by having lower RD costs. No, it was because he made like 9000 Model T's a day and he could sell each one for like 400 bucks, while the stagecoach builders that were the main auto manufacturers in the early days, took months to custom build each car and then sold them for thousands of dollars.