I have a bit of insight into this subject so figured I'd weigh in. While I understand the OP's confusion about the teacher to student ratio (especially at that age level) from my perspective that's the least of our concerns about the children receiving more attention from actual teachers.
I might prove to be wrong/jaded (and frankly I hope that I do) but I'd suggest that if you continue following your nephew's progression through grade school , you'll come to notice that the teacher to student ratio drops each year. In its place you'll notice that your nephew's parents are talking more to administration positions than teachers. Positions that likely never existed while either of us were in grade school such as 'behavioral therapist', School 'psychologist/social worker/resource officer/guidance councilor/in-school suspension councilor' etc. etc.
I can only speak for myself but when I was going through grade school & high school we had teachers, principal/vice principals (there's apparently a council of vice principles now), a school nurse, and a small number of administration that handled things such as parents calling in sick for their kids. If I were to pull a number out of my butt- I'd say for every 20 teachers there was 1 administrator. now- I wouldn't be surprised at all to learn if it's closer to a 50-50 ratio and I'll assure you that the administrative side is making 2-3x as much as the actual teachers. But don't worry about that- the local taxes cover all of the children you never had for these services since their parents aren't able to actually 'parent them'.
So that has now created a system of teachers that go into the profession with the best intentions only to learn that they'd live a better life working at places like Target or Walmart. So the turnover ratio/burnout rate is quite high (especially angled towards the 'good ones') Those that remain either become jaded themselves towards the education process and just run out their time to collect a pension and the other portion have their own agendas that they want to use their position to advocate from.
I still remember having to get a parental permission slip signed to go to a 'new' Civil War museum that opened up in our city during either my junior or senior year of High School. Today- the schools are offering 'safe spaces' for students to change into their 'gender identity' without parental influence (largely in part to the previously mentioned support/admin staff), are humoring these early teens in their 'beliefs' based off of their heightened knowledge and experience, and are using the administration to chastise the parents that find out about this after the fact and raise concerns.
And that's all I'll say about that before going on a rant myself.
-LD