An assault and battery charge will generally get you a $10K bail. Assuming the typical bondsman charges 10%, that's a measly $1,000 to be walking the streets again after assaulting someone.
I can already hear the stampede of justice troopers coming to tell me that $1,000 of emergency funds is too much to ask of your average accused criminal. How many of you would be amenable to say, a $100 charge for an ankle bracelet? Or a work-release program that allows them to attend work while waiting for trial?