Europe puts so much into their grassroots sports that you're damn near brainwashed into wanting to rep your country any chance you get. Honestly if Luka didn't play then his country would understand but he would probably beat himself up for not stepping up for his country. A lot of these guys owe what they have to their national program at various levels.
Canada doesn't do shyt for anybody. That's a big reason why guys don't care to show up. Canada needs the players infinitely more than the players need them. The only person around now that probably really benefitted from anything from Canada Basketball is RJ and that's because his Dad became an executive and his AAU team was pretty much a feeder team to the Cadet team. And probably Cory, he's always around. Canada only checks for you once you have a name. They don't build anybody.
Or when the Olympics are in Canada