By that I mean that we could also look at what 2.7 million dollars (or even that flat cost + operating costs evened out over the period of time of the study) would do, were it put towards every one of those defendants in dire conditions. To ensure for example that they have at least a temporary place to stay, social programs in place, someone to follow their case and offer a reinforced legal counsel (which is available to everyone for free for sure, but I hope nobody kids themselves about how overworked those people are - I could bet everything I have that anyone with a good income would always pick a private lawyer over duty counsel).
As for your last point: it certainly doesn't seem to be the case right now but I can very well see that entering the realm of possibilities. You can't imagine that a system that performs on paper really well and is thrown into a field where people are incredibly over-worked would end up being relied on a little bit too much?
I mean, we see that sort of thing in place for way less reliable things with people who actually know better (i.e. how many scripts and old bits of code hold together much of the world). And in the medical field the development and usage of AI is on a steady rise ("chatbots" in psychology, predictive modeling for decision making and disease diagnosis, "telehealth" assessments using data from IoT devices). If AI gave people more work rather than less, it would be of no use after all.