What Lightroom version are you running?
These options were introduced in version 6.1/2015.1, so if you have version 6.0/2015.0, you need to update.
And if you have LR 5 or older, you need to buy an upgrade.
Also, if you do have 6.1/2015.1 or later, the blacks and whites sliders will not be visible if the process version for the image is 2010 or 2003. You can then update the process version to the current version - 2012, and the sliders will become visible.
There is no version of Lightroom 6 that shows the black and white sliders for brushes or local adjustments.
This feature is only in LR CC 2015.1 or later, and you must be using Process Version 2012.
Yes, you are of course right. LR 6 has had no new features added since it came out.
felipehorn - you need LR CC 2015.1 or later to get those features. And it is only available by subscription - 10 US dollars a month for Lightroom and Photoshop. Sorry for the confusion.