As mentioned, it is dangerous and increasingly illegal to go after actual bad guys, but prostitutes are pretty harmless, so it's reasonably safe to arrest them, and 12 year old girls doing a household chore for their daddy are even safer to arrest than prostitutes.
By the way, not just in these two cases but in many other cases commented on here and elsewhere there's a clear pattern that emerges: if these stories are representative then this stuff happens almost exclusively to blacks, even though blacks constitute a small fraction of the population.
Safe law enforcement
As mentioned, it is dangerous and increasingly illegal to go after actual bad guys, but prostitutes are pretty harmless, so it's reasonably safe to arrest them, and 12 year old girls doing a household chore for their daddy are even safer to arrest than prostitutes.
By the way, not just in these two cases but in many other cases commented on here and elsewhere there's a clear pattern that emerges: if these stories are representative then this stuff happens almost exclusively to blacks, even though blacks constitute a small fraction of the population.