For what it's worth, the biker clubs drill it into your head to not resist the arrest if doing so would cause trouble for the rest of the club. In this case (the cops showed up to arrest people at a gang war) there was no denying what they were doing so they had to roll over. If they hadn't, it's likely they'd have been silenced by their own gangs in prison. Instead, the lawyers for these clubs are going to duke it out with the DA, get out who they can, and ensure the silence of the rest. This is how a high level criminal enterprise works.
Compare this to a street gang: they have no need for legitimacy in the eyes of the law, so they have no reason to cooperate, period. They don't pretend to be anything other than an illicit group and take pride in this, displaying it openly to anyone.
To put this another way... if those were mafioso or Yakuza getting arrested and treated like this, would you look twice? Then why would you for a motorcycle club, which operates under many of the same rules and standards... fuck, even more rules because these groups use the "club" label to evade the police and to operate in public.
tl;dr version - There are cultural and legal issues at hand here beyond the color of the skin of the perpetrators.