If that's the case, why involve money in it? About a third of people who are arrested cannot afford bail, while if you are rich (maybe through crime), you can pay it. Of course bail is a mechanism for differential treatment between rich and poor in the judicial system.

Right, the UK generally doesn't have cash bail, and the most recent noteworthy example where cash bail was used (Julian Assange) the accused did not in fact surrender and those who stumped up the money for bail lost their money, suggesting it's just a way for people with means to avoid justice.

The overwhelming majority of cases bailed in the UK surrender exactly as expected, even in cases where they know they are likely to receive a custodial sentence. Where people don't surrender I've been to hearings for those people and they're almost invariably incompetent rather than seriously trying to evade the law. Like, you were set bail for Tuesday afternoon, you don't show up, Wednesday morning the cops get your name, they go to your mum's house, you're asleep in bed because you thought it was next Tuesday. Idiots, but hardly a great danger to society. The penalty for not turning up is they spend however long in the cells until the court gets around to them, so still better than the US system but decidedly less convenient than if they'd actually turned up as requested.

I am not defending bail as a system. However, the system in USA relies on it. The complaint here was not that poor people stay in jail. The complain was purely about someone being able to pay bail.

> About a third of people who are arrested cannot afford bail, while if you are rich (maybe through crime), you can pay it.

This means 2/3 of arrested people can afford bail or are released without it. A case of single rich person having affordable bail is not exactly proof of inequality here. Poor people who had low enough bail they were able to pay do exist too.