I read an article, I think in the WSJ, about this last week. It basically said this was starting to show a little pre-pandemic. Shipping companies (land and sea) weren't making that much money and were cutting out excess capacity. When the pandemic hit they cut even more as orders dried up and not nearly as much was being shipped. When people realized that this was going to be an extended thing and not just a few months, they started spending money, lots of it, on THINGS. The money that used to go into eating out and travel is going into washing machines, TVs, sofas, cars, etc. It created a perfect storm: workforce issues that every industry is facing, increased demand, and years of reducing excess capacity (ships, trains, trucks, and the people to run them) lead to a backlog that isn't going away anytime soon. Increasing capacity in those takes major investment and time. That is assuming that the companies want to increase capacity. They are still thinking about when demand for shipping returns to normal. That was the cliff notes version.