Bikers don't have bike licenses in most places. They aren't taught where to ride, they ignore traffic signals, they don't try to get out of the way when traffic lines up behind them and police officers mostly do not enforce traffic laws when its a bike.
They take up half a lane and are moving at a dangerously slow pace compared to motor vehicles. It is similar to when a sailboat is in the way of a freighter, but here the larger and faster vehicle really has no place to go other than to collide or slow down. I would like to expect that they would at least behave as good as a guy on a moped, but this doesn't happen.
The laws in my state say that they should be treated the same as a motor vehicle. This is not what happens.
At least our state has added some good long distance bike paths and bike overpasses, but these are mostly used by the trendy and health conscious, not for people actually trying to get anywhere.