Officers tend to find people quite quickly—a lot of them.
You'd have to look at the stats. For sure there are people who have gone underground, and that may be a problem. In those kinds of cases, if you think this might be the kind of person to go underground, then a GPS might be useful in that instance, but not across the board. As I said, it should be for a fixed time.
Say someone comes in and makes a refugee claim. It's a family. You know the country they're coming from has really bad conditions. You're concerned at the end of the day that they might be afraid to go back, even if they are found not to be refugees. If you think a GPS would be useful, put it on them at the end of the process when they have to make the pre-removal risk assessment application, not for the whole five years they're in Canada. Limit it to the time that you think it's needed.
Again, it should be justified. It should be before an immigration judge, not a CBSA officer arbitrarily deciding to impose it. It's too intrusive.