Totally depends on your definition of street racing.
To me, street racing is late night at a secluded industrial parkway with no traffic on a three lane wide road. To others, street racing is going from a 40 hit on the freeway over and over...
Most of the deaths you see in the paper are idiots in Civics weaving in and out of traffic like jackasses and eventually hitting someone. I don't think anything has changed with true street racing (as what I define it as) over the years.
I can't speak for others but I had an 11 second car at 18 and never had any problems. I've never been in a single accident in my life aside from jumping off the R6... age doesn't effect responsibility IMO. There are 18 year old kids that are more mature and make smarter decisions than 30 year olds.
The one thing I will say that's changed, Americans as a whole are far dumber these days and less responsible. Everyone wants to blame their faults on anyone but themselves...