I think you express some very real concerns, but they don’t explain the crime data. Crimes are down the most sharply for the crime categories which must be reported: murder/non-negligent homicide and vehicle theft.
Yes I saw that in the data. I have no good explanation and the system has been around for years so that it should have stable collection techniques. One other explanation is that hardcore drug use has gone country. Big city crime labs may have some effect on criminals moving to smaller locales.