Electronic monitoring is very good to follow movement, but it doesn't prevent someone from disappearing or going underground, so for the purposes of immigration, where it's important that we know where the people are, that would not always be the best option. In some cases, other conditions of release are just as effective, such as curfews, or reporting conditions, or even bonds—monetary bonds or performance bonds are just as effective.
In most other cases, it would be excessive and not necessarily cost-effective, because it's not just the bracelet. You need people to monitor the screen and to respond to the alerts and the alarms 24 hours a day, seven days a week.
You have to take those things into consideration. Quite often, a low-risk population wouldn't warrant that type of response.