Actually there are many benefits to the LEO for having their interactions recorded. The use to the organization when addressing citizen complaints and providing evidence are pretty widely acknowledged. [0] This isn't just about 'catching cops doing bad'. It is also about having more reliable evidence to use if a complaint or a situation of one person's word against another arises. The fact that it can also prove wrongdoing by a LEO should be thought of as a side benefit.

[0] http://www.theiacp.org/LinkClick.aspx?fileticket=5k3IK9SZuz4...