When many US cities have higher homicide rates than Rio, I think anyone attempting to paint a picture of "Crime is not that bad, here is the data" is intentionally missing the serious problem areas. I would also say, decriminalizing a shit load of crimes also does wonders to lower crime rates. How many televised flash mob robberies to people need to see to understand something is broken in the USA?
I'm not saying that crime isn't bad. U.S. crime is quite bad - especially our murder rate, which is far worse than other First World countries. What I would say is:
1) U.S. crime was even worse back in the 1980s-1990s. Going earlier - it was better back in the 1950s than today, but worse in the 1930s.
2) One shouldn't judge crime rates (or lots of other things) based on watching television.
Anyone here ever watch that show "The Wire" It was great from what I remember, but much like robocop and detroit, it actually got WORSE than depicted in the show. Anyway, one thing the police brass and politicians always are talking about is "massaging the stats" and making it look as if crime has not increased, or in some areas decreased. I think that was probably a reflection of harsh reality instead of creative writing. I would also say, things like a homicide stat to compare to the 90's or the 70's are not as meaningful, since if there is one thing doctors in cities can do these days, it is treat trauma and gunshots. I think lots of dudes who would have been dead in 1994 get shot and recover these days.
I love The Wire. It's an amazing show, and yes, there is at least some reality to it. It's based on David Simon's non-fiction book "Homicide: A Year on the Killing Streets" from when he spent 1988 with the Baltimore homicide unit. That book was adapted to television twice: in Homicide: Life on the Street (1993–99) and in The Wire (2002–08). So note that when Simon was writing about police massaging the stats - he was talking about doing so back in 1988. Massaging the stats is something that has always happened - it doesn't explain the huge drop in crime rates from 1990 to the early 2000s. Also, the national NCVS was established decades earlier under Nixon to address local police manipulation of stats.
Sadly, while many other U.S. cities like New York and L.A. have seen decrease in crime, Baltimore homicides have only gotten worse since 1988.
As for improved treatment of gunshots... If that were the primary factor, then I'd expect to see a downward trend in homicide but none in other crimes. But the national trend went down dramatically in most crimes from 1990 to the mid-2000s - including robbery, burglary, assault, and arson.