No teacher would say that twice to my child if I knew about it, largely because I probably would have called her out of class right then and told her she could scold him for being late but in NO WAY was she EVER going to compare herself to me and cut me down to my child like that. Would she like it if I went into class and told the students how awful and ineffective she was? She might argue, but I don't tolerate this and the one teacher who tried it when Wiz was in 1st grade learned the hard way to back off and apologize or she was going to have a terrible struggle on her hands because I simply would NOT tolerate it. As none of the other kids' parents had the fit I did, and this teacher OFTEN told kids how their parents were too lax or nice or let them get away with things, I don't think it is cultural as much as a matter of respect. I don't CARE if the teacher likes me, but I WILL be respected as the child's parent. Period. If a teacher does't like it, they are FREE to quit or ask to have my child moved to another class with a teacher who will not purposely tell children their parents are lazy slobs who don't deserve their respect (the child's respect - the teacher used those words exactly and often to the children).
I remember hearing the parents of a friend talk about the struggles they had. This was about 1978 or so and their son who was a bit younger than I was was the first kid I knew hwo had adhd. He was a real shock to any teacher. It was a little known disorder and he still is the most hyper adhd child I have ever known - far more than most kids who are diagnosis'd with adhd. They struggled and he was in trouble a lot and he hated school even after he got medications, mostly because back then NO ONE believed he couldn't control it. It was really tough for his parents, and a lot of teachers tried the "your parents may let you xyz but it won't work here" and that NEVER worked with him because mostly he was UNABLE to do what they wanted.
so I think I have some sympathy with what you are experiencing. It was far easier when Wiz was diagnosis'd because it is well known here and he wasn't the first child with adhd his teachers had experienced. He was the first hyperlexic child (he was reading shortly after he turned 3 and by kdg - age 5 - he was reading chapter books with 100-200 pages in a day or so) and they expected him to behave like a child who could read at that level when he just was not that mature, was not even as mature as his age level except in reading and use of language. It was a struggle to educate them because the teachers did not believe they NEEDED to learn about this or him.
I am sorry it is so difficult, and I don't know if this woman is a good thing for J to experience. But if it isn't harming him, then it will help him grow. Maybe. I guess.
I just know I would have gone off on her if I heard that nonsense and she would have regretted it because if she gave me anything but a sincere apology I would have gone to HER boss and HIS boss and the school board about how inappropriate it is to criticize a parent to a child, and she works for ME, not the other way around and she better keep her opinion of me far away from my child. Of course I did have a leg up in that a number of the school board members were relatives (great uncles) who were NOT happy and felt it was terribly disrespectful for a teacher to criticize a parent in front of their child. That is just a no-no, just as parents are not supposed to tell kids that we think their teachers are idiots.
I DO think walkie talkies are a good idea, though you may need to put a strap on one for J to wear around his neck or to attach to a belt or belt loop. He also has to be sure it has fresh batteries when he leaves, or else he has to come home as soon as the batteries die or have a spare set with him in a pocket. They do not work on cell phone technology, but on radio waves, so unless there are deep valleys or steep hills he should be fine. This is as much a physical problem, him being out of reach, as anything, so a physical solution, aka walkie talkies, is as good as anything until he is mature enough to not wander off wehre he shouldn't be.
You must set some rules for the walky talkies though. What happens if he forgets them, or leaves them somewhere? What happens if the batteries die and he doesn't return home immediately for fresh ones? What happens if you call him and he doesn't answer, or he says he is coming home but he gets distracted or decides to do something else instead? You need to work out any potential problems and the penalties BEFORE you let him loose with them. He should be told ONE TIME that he must take the walky talkies and he must always keep them with him and on, and if the battery dies he MUST return home immediately. He is easily old enough to not forget these if told once. If you EXPECT him to remember and act as though he does, then he will. Don't let "I forgot" get him out of whatever the consequence is (not being able to go out of your sight for a week should be enough, in my opinion) and he WILL remember them because he won't watn the consequence. If you keep telling him, or you let "I forgot" or "I didn't know" get him out of the consequence, hten he will continue to not bother to remember the rules and he will continue to not use them appropriately.
Wiz had walkie talkies at one point because he kept wandering off to "play" on an old walking track maintained by the university. The entire town uses it, and it is not a great place for kids at times because the teens have places out there where they do things they hsouldn't. After an older kid beat the koi out of Wiz an dhe had to call Gpa with the walky talky to come get him, he never forgot them again. He could NOT believe that anyone would do that, and I am sure he was mouthy and egged the kid on with nasty words nad also taht he hit back pretty hard, but he still was pretty hurt and upset. This is why we didn't want him playing there - we had been warned by a friend who is a cop taht the teens were doing some really unsafe things there, including hurting each other and animals and younger kids with fireworks. Wiz was supposed to be somewhere else, but went to the track instead and got hurt and did NOT want to call but couldn't get home with-o help and it was getting dark. He got a punishment because he went there after being told not to, he couldn't leave the yard with-o an adult for two weeks. We thought he got off light, and the beating was the worst punishment. He didn't agree, but he was 9 and we didn't really care.