According to the GSMA last year phone theft (which arguably has much more part serialization and anti-theft measures implemented) has been a steady 1% of smart phone users worldwide. It does not seem these attempts to lock down systems are successful in reducing theft. https://www.gsma.com/solutions-and-impact/industry-services/...
However I wonder if they have had an impact on data and financial theft. Which things like part serialization wouldn't affect but system security measures would.
In the early days, iPhones being both extremely popular and expensive made them pretty big theft targets and Apple was getting pressure from the various state governments to "do something" about the increases in phone theft. At least according to NY and CA, the activation lock alone in iOS7 caused double digit drops in the iPhone theft rates: https://appleinsider.com/articles/14/06/20/police-say-ios-7-...
However I wonder if they have had an impact on data and financial theft. Which things like part serialization wouldn't affect but system security measures would.