The bottom line is that when you shut down economies around the globe for good parts of a year, you are going to get all kinds of distortions. The economy is a finely tuned instrument. Clueless politicians may think it is a simple turn-off/turn-on situation. But it is about major changes in demand and some sectors of the economy where it takes time to adjust to the new supply and demand factors.
Below is a great interview with a supply-chain services expert that will help you understand some of the transportation issues out in the field.