I agree. I think it comes down to doctrine and how the players are taught. They are a containing defense rather than an attacking defense.
I think part of the reason they don't attack the ball and create turnovers is that they are coached to keep everything in front of them and so they are reluctant to try to make plays on the ball.
Or maybe it really is as simple as the players that they have are not skilled enough or confident enough to make those plays. Confidence plays a big part.