Thanks for the response.
Seems like an odd way to do things...but the judicial system is odd I guess.
There is almost always a good reason for any given legal policy - not that the policy always fits the circumstance at hand.
An accused is entitled to bail he can afford. If bail is set too high, then the accused is imprisoned until guilt is established. Intuitively, that's okay for those who are guilty in fact, and are found guilty. Why have bail at all, for them, just jail 'em.
But if bail is set so high that few people can pay it (say, 100 million dollars, across the board), then everybody swept up by the state sits in jail until trial. So, the general rule is a setting of bail so high that if the defendant doesn't appear voluntarily, he "loses everything." At the same time, he is allowed to put his "everything" up as security for his promise to appear.
If bail is set low, then it isn't much incentive to appear voluntarily - although fleeing is a serious offense of its own right.
Anyway, sliding scale, or accounting for defendant's assets, is common in "big bail" cases. Not so much for misdemeanor crimes, where bail is set low enough (no sliding scale) that almost everybody can afford to pay it. No sense in bothering a judge to find the amount of bail for 200 DUI's a week, etc.