I know the question about coppers flaring wasn't for me, but I have to give some input because I've noticed the same things!
Perhaps many coppers are a peaceful and intelligent lot, because mine doesn't flare either, unless you really force him to do so with a mirror. He'll even stop whatever he's doing and swim right up to you if you beckon at him with your finger :) If my boyfriend or I are using the computer next to him, he'll sit on the leaves in the corner closest to us and watch. It's also clear that he recognises the colour blue (the cap on his bottle of food is blue) - he'll swim up to the corner of the tank in which I feed him and start begging if he sees anything in that shade of blue!
At the moment, Jasper may not flare because he's still getting used to his home and "defining his territory". When I moved Modi into a new tank, he was scared to death of his own reflection. Wouldn't flare, got stress stripes and all.
I'd be quite curious as well as to if personality traits and level of aggressiveness in bettas are completely random, or are based on their tail type or colouration.