Why did Americans get panic buying toilet paper when they encountered disasters?

In the COVID-19 epidemic that swept the world, panic and rapid spread of the epidemic caused toilet paper to be sold out in many countries. Take the United States as an example. No toilet paper can be seen on the shelves of major supermarkets. Simply put, there are only two reasons.
First, there are only two places where toilet paper is produced in the United States. Almost all toilet paper is imported to the United States. Secondly, the two products that produce toilet paper are both in the central region, and it takes a lot of time to deliver to densely populated cities such as California and New York.

The way to buy toilet paper in the United States is different from that in China. Almost all the toilet paper in the United States is bought in a pack. All the toilet paper in the United States is a dozen (12 rolls per dozen). It is equivalent to buying 12 packs of toilet paper, and you bought 24 packs of toilet paper at one time. But in the U.S. there is no choice. They just don’t take them apart and buy them. For example, I buy two copies of the rest of my stuff, so why not buy two copies of napkins? I have never seen that news station report gave out more than three dozen toilet papers, almost two dozen at most.

The other is inventory. Don’t think inventory is not a problem, because there are not so many vehicles to help you transport toilet paper. Why do I have to send you toilet paper with a unit price of only 10 yuan for a dozen beef? The amount of profit that can not be made, naturally each store has different strengths for the roll paper purchase. For example, if there are 100 customers in a store every day, the ratio of a single food (category) will be 2:1, because it is very likely that one person will take two or more items, and if there is enough food, the ratio of toilet paper is only 0.8: 1. Because the store has calculated that not everyone will take a bucket of roll paper when buying things, so the inventory they own is reduced. Naturally, we cannot cope with this emergency situation.
Web paper is a very magical industry chain. You cannot print more or less. Too much printing will lead to accumulation of warehouses, and less printing will lead to insufficient supply. Don't think this is simple. The larger the object, the smaller the controllable range. Rice is also the same reason. Don’t forget that China’s epidemic has just begun, and the market price deficit is even worse.