“How is a ‘cash bail’ part of systemic racism?”
Because racial bias effects bail decisions.
“How else is anyone supposed to pay their bail? Check? Credit card?”
Check and credit card are both ways of transferring cash. So like @stanleybmanly said, it’s not about the method of payment. One alternative to cash bail, however, is property bond. In jurisdictions that allow it, you can use your property as collateral. And just like the bail bondsman that @LuckyGuy described, you don’t even have to hand over the property. You just promise to surrender it if you fail to meet the conditions of your bail.
Not everyone will have enough property to secure their bail in this way, but it has the advantage of not requiring an actual transfer or loss until one has actually violated the terms of their bail. Because let’s remember that bail only applies to people who have not yet been convicted of a crime (and therefore have a legal presumption of freedom and innocence).
Of course, we could also eliminate the whole notion of paying bail in favor of other methods of securing someone’s appearance in court. House arrest and electronic monitoring are two alternatives already in use, and they don’t cost the defendant a penny. That wouldn’t solve everything—there’s still racism and classism in the algorithms we use to assess risk—but it would cut down on the effects of pretrial detention.