The whole project is futile and serves only to placate anti-immigrant feeling.

Tags do not prevent someone from absconding - they could simply remove the tag and disappear, into those parts of society where people are able to live without paperwork.

The only reason tags work is because most petty or white-collar criminals have no interest in disappearing, and can be easily found if they do. They only serve to enforce bail conditions such as not going out in the evening.