There are a small number of people who think cars are just produced as soon as you order them from the dealer and then they’re shipped to you. This author seems to think that’s what happens or else he wouldn’t be so worried about cars building up in ports.
That’s what ports are for. Automakers estimate how many cars they think they’ll sell and then they produce that many, on schedule, and park them outside the production facility. Then they’re taken to a port. Then they’re shipped to the markets where they’re sold, the cars are parked, and then shipped by train and truck to dealerships.
Below are parked tens of thousands of cars at Royal Portbury Docks, Avonmouth, near Bristol in the United Kingdom. If you look on Google Maps and scan around the area at say 200ft you will see nothing but parked up unsold cars. They are absolutley everywhere in that area practically every open space has unsold cars parked up on it.
The port in question is within about 200 miles of a population of 45 million consumers and handles roughly 700,000 vehicles per year. They do not individually unload and ship each car as that would be wildly inefficient. Instead, they ship many of them, in boats, and then unload all of them, and then send them to their various points of sale.
In the same port you might find containers full of iPhones and iPads. That doesn’t mean there are millions of unsold iPads and iPhones, that’s just how almost all manufacturing has worked through all of history.
One of these rail yards references in the piece, which you can see here, is barely half full (Europe’s car market is still slowly recovering).