This is due to fear of screwing something up (Mortal sin in the modern age)
Zoomers grew up being told children (themselves) were a huge burden. This was proven true when their parents got divorced.
Now their lifes goal is to not bother anyone, best way to do that is to not act

This is also why they are so kind (non-confrontational) to service workers. They view themselves as a burden.
“This worker wouldn’t have to work a job they hate if I wasn’t here buying things”
“No I wont ask the waiter to fix my order, they are busy enough already”