The tea party protests involved (and continues to involve) hundreds of thousands of ordinary Americans concerned about the rise of government's role in their lives. The media has followed the lead of the Dems' attempt to portray these folks as radicals.
The media commentariate's claim was as follows: oh sure, the crowds were peaceful....for now, but such opposition may be sowing the seeds of future violence, albeit indirectly. As such we must question the legitimacy of this dissent. We need to dig deep and dig hard, in wall to wall coverage, searching for any signs of the potential for violence.
Meanwhile, leftists at the G20 summit (an event which inherently attracts international exposure), engage in physical attacks en masse against the authorities - actual politically motivated violence against the state,
and the media averts their eyes.