I mean at 7 years old, you don't really care either way. I moved to the country when i was 6, so I wasn't even native and had no true cultural ties, but even then, a lot of kids, particularly white, but also a lot of maori and other pacific island kids, didn't really care, no one kicked up a fuss as it was more of a time to goof around then anything. We kinda all half assed it because again, it was more so the school could say the encouraged maori culture, as was common place. Honestly it wasn't so serious, obviously if you flat out refused, then you would be treated the same way as if you refused to participate in any lesson or event, Maori or not, the exact same way any other school around the world would. Also it wasn't like it was a frequent thing, it would be for like an hour or so on a thursday afternoon for like 6 consecutive weeks, then the rest of the year we did other weird shit and honestly, it was something different to do than normal primary school shit like being read to by a teacher while you sit around or learn about dinosaurs. I mean that same school also had the entire student body learn the recorder and do a big performance for an end of term assembly, so there was all sorts of wacky dumb shit that had no real impact on education and was very clearly nothing to do with Maori culture, To compare it to the UK its no different then having to sing christian hymns during assemblies, even if you weren't religious, in fact i had more teachers who told me off for not singing about jesus despite not being christian then i did teachers telling me off for not doing the haka despite not being Maori, its just a different culture that does different things.

Id then move to a different school and it would only be done by kids who gave a damn about the heritage by joining the haka club and the rest of us would go to a sports club or motor cross or something else. As i said, it's on a school by school basis. Once you hit highschool, its entirely elective, we did it 1 year in PE for a few weeks in between doing basketball and learning about drugs and alcohol (which PE itself became an elective class after the first 2 years of the 5 years of highschool, as the school recognised that a 15 year old may not wanna spend time running track or playing tennis, and instead wants to spend that time fixing cars or learning business and economics or psychology etc. in that time) but during that time, you would just have fun with it, it wasn't taken too seriously and was just a way to participate in the culture, we would all have a laugh with it, even the teacher.

Also, not gonna lie, it was kinda fun. As a kid you get told You'd get to make as much noise as you want and pull silly faces rather than be sat behind a desk and all you had to do was copy the dude in front and say words you don't understand. I know that doesn't sound important but at 7 years old nothing you are doing is massively important besides learning how to read and learning how to count. Obviously if you don't grow up with it, it might seem weird or something you shouldn't participate in, but you could say that about a large amount of school.