You're conflating a few different things. Being able to pay bail so you don't have to be in jail while you wait for your trial doesn't get you out of having a trial, and has nothing to do with needing lawyers.
What the parent was referring to is the fact that if AI starts to consume the low-end (starting with traffic tickets), actual lawyers for trials will become even more expensive, and thus poorer people will actually fare worse because they will lose their already-limited access to human lawyers. Yes, their case might get handled with less hassle and cheaper, but the quality of the service is not -better-, it's just cheaper/easier.
Or maybe we only end up using lawyers when they're actually needed, and they become less costly for things like criminal trials. Think on the doctor whose routine cold and flu visits are replaced by an AI. Now they have a lot more time and bandwidth to handle patients who actually need physician care.
We can't just assume it's going to go the worst way. Neither outcome is particularly more likely, and the human element is by far the most unpredictable.
To wit: I was listening to a report yesterday on NPR about concierge primary care physicians. The MD they were interviewing was declining going that direction because they saw being a doctor as part duty and felt concierge medicine went against that.
It seems to me you're the only one conflating things? Grandparent didn't say anything about getting out of having a trial, or about needing lawyers. They're talking about how people with money can use it to avoid spending time in jail, and gave a perfectly valid example of someone rich doing exactly that.
That is pretty bad example. In theory, bail should be affordable to the individual person. It is meant to be insurance that you come back for actual court date.
The outrage there is bails being set to unaffordable sizes for poor people. OP was picking out the case where bail functioned as intended.
What the parent was referring to is the fact that if AI starts to consume the low-end (starting with traffic tickets), actual lawyers for trials will become even more expensive, and thus poorer people will actually fare worse because they will lose their already-limited access to human lawyers. Yes, their case might get handled with less hassle and cheaper, but the quality of the service is not -better-, it's just cheaper/easier.