Dear Redstone,
When I was a teenager, I had a parent just like that. Dad would
sometimes (very rarely) say sorry, but my mother never would.
Perhaps it stems from their belief that they should appear
infallible in front of children, & also, being children, we
should accept the fact that they don't ever need to apologise,
& we should respect them notwithstanding any mistake they
had/have made, & will continue to make.
I'm 28 this year, & I still experience the same problem as you.
I suppose the habit is too ingrained in parents of their
generation. We hafta accept it, they are probably too set in their
ways to change. The only thing you can do is to grow up, &
become different parents to your offspring : )
Hang in there.
FeowFeow