While I generally agree, the devil is always in the details, and having no specific knowledge I do not reject the reported drop in crime, but I certainly do not accept it as gospel.

Tangentially related anecdote: 15 years ago, a friend of mine bought a house on the (wrong side of an) edge of a crime reporting district in Philadelphia for $80k. Across the road (which wasn't a highway or anything, just another inner neighborhood road), an exact copy of the same house (same developer, same year, same project, same layout, same everything) went for $200k at the time.

Three years later, the crime reporting districts changed, and his house (and a few others) were reported in te better district. His house value changed, practically overnight, from $100k to $240k.

Ergo, report methodology can effectively affect related value significantly. Quantum measurement effects on a macroeconomic scale.

If it was one set of figures from one country then you might have a point, but you are effectively describing noise and for such a wide range of crimes across such a wide range of countries you would expect the noise from reporting changes between different jurisdictions to more or less cancel out.

I am not arguing or contradicting you in any way, as I do not have any specific knowledge - but there are globally misreported (or misunderstood, I won't argue semantics) cost-of-living figures, without requiring conspirators or any centralized planning - do not rule out global bias in reporting just because a mechanism for such bias is not evident.

I don't rule out bias, I am just noting that in this case it would seem unlikely to all be pushing in one direction for the reasons I stated.