Rockets don't draw fouls as well as the Lakers, particularly with Yao out. I think image has something to do with it as well.
What does it matter....it's not like we make our FT's anyway.... But to answer, the Lakers seem to have more speed throughout their entire lineup. They can get by Jazz defenders, which causes foul problems. Additionally, Kobe gets more respect than T-Mac. I always laugh whenever Laker fans feel like the refs rob him.