Random thoughts on this issue:
1) Putting up your house is such a PITA in our area, must people who start doing it throw up their hands and pay the bondsman. It is basically done like a HELOC, requires title exams, etc, can't have any liens on it, and the docs have to be prepared, executed and then recorded so it is faster to just pay the bond company their 10% unless you have a huge bail.
2) I am not sure that blacks are the victims of racism in the process so much as they are less well-established generally to come up with money fast and a lot of them simply have records that drive up the bail amount so the racism is probably more secondary to just blacks still have a fairly sucky lot in life as a whole.
3) As imperfect as it is, some of these people need to stay behind bars to dry out, sober up, break their stealing sprees, etc. In my state at least you get credit for time served so it is not all wasted. Often they are about done with their sentence by the time it gets imposed unless they are doing major felonies.