Post play is generally reffed differently because of the different style of play. Inside, you are trying to use your body to get position on your opponent, outside it is all about speed. Contact on the outside neutralizes speed, which is why it gets whistled quicker (though I thought Jameer took a lot of contact last night, and to his credit said nothing). Inside, the game is constant contact, you do not want them whistling it.
The refs could simply point out to Barnes that his interior players play differently than his outside players
and they are probably coached to do so.