Using someone else's connection may be considered theft unless it is made it clear they are willing to share it. Leaving a wireless network unsecured is effectively inviting people to use it. The individual is at fault as ignorance or stupidity is no excuse to blame others.

If you don't want people to use your connection: don't broadcast your SSID and secure the connection. Surely the police have got more important crimes to resolve and what a waste of tax payers money!

A collective WiFi approach would be cheaper for everyone and a lot less socially divisive. In Europe public WiFi access is the norm with free hotspots available for public use.