I'm not sure there is no incompetence involved when the same process is much faster basically anywhere outside the US. That is a question not answered (not even asked) in that episode if I remember correctly. I don't mean the human factor (that will be resolved in some time) but the technology used.

Chip card transactions do take a very long time in the US. If I had to guess as to the reason it would not be network or back end processing (seems way way too long, and too consistent to be due to those factors), but probably the time it takes the card to run crypto. Perhaps they use cheap cards with slow cpu but also big keys for fear of attack?