Car thefts are reported to insurance companies. Murders tend to be reported.
We also have the National Crime Survey, which simply asks people if they have been the victim of various crimes in the last year. No interaction with police whatsoever. This also tracks a huge drop in crime despite people insisting that "crime is up", especially when asked about the country broadly rather than their local region.
What's your argument? That we're always privy to the truth, and that statistics are never in error, and are never crafted by people in service of an agenda? Okay, I guess, that's great for you. No reason to question anything, or think critically for yourself.
We also have the National Crime Survey, which simply asks people if they have been the victim of various crimes in the last year. No interaction with police whatsoever. This also tracks a huge drop in crime despite people insisting that "crime is up", especially when asked about the country broadly rather than their local region.