A friend of mine who visited Japan made this observation: "They had a person doing everything. If in our parking garage we'd have a screen pointing where to park, Japan would have a man waving a light stick."
My theory is that at least some of these people are needed for managing the rush hours or possibly big regular events such as fireworks festivals that bring in hubdreds of thousands of people.
So normally they might seem unnecessary yet their role might be crucial for directing the people flows during the rush hour.
I noticed this as well visiting several years ago. For instance, even though the process for hotel check-in and most other services was automated with these fancy kiosks, they still had two people behind the desk in case you needed help.
In the west, humans are becoming less employable as they're displaced by automation--https://www.youtube.com/watch?v=7Pq-S557XQU is a good video if you haven't seen it, and it's from before AI/ML took off! Japan seems to have mitigated it by making automation an addition, instead of a replacement, in many cases. It's certainly not the efficient, capitalist thing to do, but maybe it's the better thing to do.
So normally they might seem unnecessary yet their role might be crucial for directing the people flows during the rush hour.