Has been the case since the late 90's early 2000's when they had to adjust to new law enforcement tactics.
Criminals adapt. In the 90's they wore specific colors, and intentionaly stood out. There was no way to confuse most gang members with others. Some have been slower to change, but for the most part that is a thing of the past.
Law enforcement got all sorts of green lights to treat such people very differently under the law, and fast track thier due process, even having policies many places that seem downright third world in dealing with gangs.
It is always smart to pay attention to how undesireables of a time period are treated under the law, for it is usualy in such realms that the protections of us all are on the front lines and can be removed one piece at a time.
Labeling someone a gang member/ street terrorist, or organized crime member allows for very different treatment under the law many places. So LEO often do all they can to apply such labels to as many as possible, even people that just know someone who is a gang member or have a friend who is one are often labeled as one themselves. Property can be siezed, people can be denied various rights and numerous enhancements can be applied.
Many "gang members" or those from high gang areas that will return to them afterwards join the military, get good training with weapons, and come to appreciate the uses for various weapons, various tactics, and things like body armor for different high risk tasks. They then return to regions with skills highly suited to a life of crime if that is the path they choose. For each one that then leaves the military and chooses such a path they teach many others these same lessons back home.
This is especialy dangerous in a "police action" type of scenario where our military is ruling over a region, practicing and using many tactics invaluable to gangs at home. A lot of experience in home invasions can be achieved by raiding homes of people in Iraq, and learning to control people that do not want to be controlled. Learning to use fear tactics to keep people in line, and learning to make examples of any that lash out.
The new FBI report on deadly force encounters experienced by law enforcement officers highlights this fact. They even train force on force with paintball guns.
Or airsoft also quite popular and available now.
Yes many have training, and they also blend in better with other citizens, not wishing to be highly obvious and unique like in the 90's. Your average college student and gang member often dress the same way now.
Our legislators have helped as well. Firearms such as the Tech-9 variants, a very difficult to use and generaly inaccurate firearm had gained a reputation among criminals from back when they were readily converted to fully automatic fire by someone with no mechanical skill.
Yet the newer versions were not readily converted, yet still sought after due to reputation, and probably the menacing appearance. This left many viewing some serious pieces of junk as ideal weapon platforms. A win as a good guy.
No longer. Now after being forced to make do with superior platforms, having "junk guns" removed many places etc Organized criminals have been forced to use good weapon platforms, and have greatly improved skills.