Obviously you weren't at school that long ago, because if you were your English teacher would have been a proper English tecaher and would have rightly taught you that you should never start a sentence with a conjunction in the rich language of England".
You obviously went to one of those schools with the modern breed of Guardianista teacher who thinks that the teaching of grammar isn't important. That's why kids today leave school knowing sod all.
It's things like this why our schools need to be cleaned up of the lefty, PC, Elf N Safety-obsessed teachers which dominate Western schools today and proper teachers sent back into the classrooms. Our kids leave school knowing sod all about English grammar and maths and everything about "diversity", "equality" and "always wear goggles when playing conkers".
It's no wonder education in the West is lagging behind that in the Far East when we have your lot teaching in them.
Oh brother.
Obviously the teacher knew enough to pass on to me, that I realized that normally sentences don't start with But. If I cared enough I would have avoided doing so but in all honesty I don't. Unless I was writing a paper or something else important, I write how I speak and quite often sentences start with "But". Don't like it, too bad, but don't blame my teachers for it.
You do realize, too, that making assumptions about people and situations just makes you look like the idiot troll you are?
Sadly, I do agree with you that "proper teaching" needs to be done in the classroom and it's sad that this isn't happening. But then I believe the entire education system is fked anyway and if I had a child of age to be in it, well, they wouldn't be.