Dunno about US experience, but for someone coming from Europe like me favelas that I've visited in Rio surely left impression of very dangerous places - and I grew up in Serbia in 90s, been through wars and all that shit and anarchy, and had my share of street education. Now, it's quite possible that they have less crime than some other neighborhoods, but that's just because gangs keep a close grip on their territory. As long as you play by their rules you can live your life sort-of normally. Problem with living in such surrounding arrises when you're forced to go against them, as there's no law to protect you, so you're fully at their mercy. That's a HUGE difference from Santa Monica or Beverly Hills, and much more like living in Somalia.

While I know Santa Monica used to have a huge gang population about 10 years ago in the neighborhoods between Santa Monica College and Santa Monica High School and generally south of the 10 freeway, that area has since gentrified quite heavily and LAPD maps shows insignificant gang activity in those neighborhoods.

I would be very surprised to see that there ever was any significant street gang activity in Beverly Hills, since that municipality spends a significant amount of money on street patrols to keep criminal activity low. Moreover, Beverly Hills is a fairly racially homogenous city...

Can you share a link to that paper please? A DOI would do...