The BCG vaccine is only effective in preventing severe illness and death in very young children (like under the age of five mostly). Kids only get TB if there is a lot of TB floating around infecting them. So in areas with very low TB transmission rates (like the United States), experts have determined it doesn't make sense to vaccinate people at birth, since their chance of developing TB before five is almost zero.
But if you're born in a region with lots of TB transmission, it does make sense to get BCG at birth. Unfortunately, it won't protect you in adolescence or adulthood, though.
BCG is currently the only vaccine for TB and it's over 100 years old. There are promising vaccines on the horizon, which is VERY exciting, but it's worth remembering that we already have lots of strategies for preventing TB. Just offering people (especially kids) adequate nutrition is a way of preventing TB. (Around half of all people who get sick with TB are malnourished, and this is an especially profound problem in children.)
We can also offer close contacts of the sick preventive therapy, which is a course of antibiotics that ensures they won't get sick. So yes, we need better tools like new vaccines. But also: We HAVE good tools; we just fail to implement them because we've decided to live in a world where we accept malnutrition and inadequate access to medical care, even though we know there are plenty of resources to provide adequate nutrition and medical care to all humans. Those resources are just distributed unjustly.