Overall in my experience, they're not consistent in applying the policy that they even have, and I've heard testimony of a CBSA officer who called it guidelines after justifying a search of a cellphone that was not placed into airplane mode.
So we have a law, the Customs Act, the provisions of which were drafted before the 1980s when none of this was contemplated, and the definition of a good includes a document, when at the time, generally, a document was referring to a bill of lading, so the document of title related to the widget, the box of whatever it is that you're bringing in. So according to their reading of the law, they can look through a cellphone; they can observe any document, and they can do whatever they want with it without any even suspicion, without any reasonable basis, and it's just part of the continuum of their secondary screening.
And they have a policy that says they only do it as part of an escalation, and they only do it if they have reasonable grounds to suspect or reasonable grounds to whatever, but the law that they're operating in doesn't do that.