Bail is set at an amount high enough that people can't afford to lose it, and thus show up to be prosecuted for a crime. If you set bails so low that most people could afford them out of pocket, they'd be so low that the risk of loss wouldn't have any deterrent effect. 60% of Americans couldn't cover even a $1,000 unexpected expense: https://www.cnbc.com/2018/01/18/few-americans-have-enough-sa....