IMO, the public is not told about certain crimes for many reasons. 1) public outcry, 2) panic, 3) people will avoid certain areas (say Galveston) and it hurts tourism, 4) some LE will actually have to do their jobs (oops, did I say that), 5) public will learn there are people in LE positions that don't have a clue what they are doing (incompetence/ignorance), 6) lack of resources/man power, 7) corruption, cover-up, ... oh yes, there could be many reasons why "I never heard a thing about those things going on in my backyard."
On the other hand, there have been cases that have been so quickly solved that blow my mind at how awesome of a job LE did in making an arrest. There are some dang good competent LE out there! We need more of that them for sure!
The rape kit DNA screenings still blow my mind! It is not isolated only to Harris County, it is a national disgrace. The technology is there but it is obviously not a priority in our country. Does that mean that rape is low priority, the victims don't matter, that it is not really seen as a crime, and/or the victims really do not matter? I think about the women that recently marched in DC and wonder where their priorities really are; where is the public outcry!