If you compare CBSA with other national security organizations, you'll find that there's no civilian oversight mechanism.
If you look at what CBSA does for a living, my contention is that it is not a tier one national security organization. It does not use the same methods as do CSIS and CSEC. It doesn't work in a top-secret environment. It collects taxes, it deals with immigration enforcement issues, and it secures the border. It is a net user of intelligence and not a net generator of intelligence.
When you dissect what CBSA does, you will find that its immigration role is closely monitored by the IRB, for instance. Its customs role is closely monitored all the way up to the Federal Court. If there is a gap in public confidence, it's around public complaints. It's around the actions of officers.