Citylaw brings up some good points.
Attrition rates have to be separated into academic/non-academic attrition, otherwise they make no sense. For example, I graduated from a part-time program where many of the students were balancing jobs and families along with law school. Our academic attrition was pretty low, but we had lots of people drop out because they couldn't handle the pressure, the expense, or they transferred.
Of course, at some lower ranked schools academic attrition is high because they're admitting people who didn't get in anywhere else. There are two ways to look at this practice. The conventional wisdom seems to be that these students are being ripped off by being admitted then failed out.
The thing I don't like about that theory is that it assumes that people have no personal agency whatsoever. No personal responsibility, no decision making power.
No one forces anyone to go to law school, and the requirements and expectations are available to anyone who takes five seconds to google them. Another view is that these schools are giving people an opportunity that they wouldn't normally have. And yes, there is some risk involved. But if the student works hard and dedicates themselves they will likely graduate, pass the bar, and realize their dreams.
Remember, a large majority of the people who begin law school will graduate and become lawyers. I meet lawyers literally every single day who couldn't get admitted to high ranked schools, went to a low ranked schools, and are successful practicing attorneys. I know quite a few who put their T1 counterparts to shame. It's all about the level of dedication you're willing to invest.