I think that's a good point, where you tie privilege to the use of an application and people are left out as a matter of the digital divide, whether we're talking about seniors, the homeless or other circumstances where people don't have access to the technology. That is a real challenge that would need to be overcome.
But, when we're talking about initially what is effective, I wonder, the go-to to voluntariness... and I say this as someone who's been incredibly vocal and supportive of privacy overall as a parliamentarian, but if we're not even going to get in the door of any efficacy or usefulness out of this because of the barrier of voluntariness then.... I'll use an example here maybe. I read the privacy commissioner's statement, and de-identification is an incredibly important principle, but then they also note that de-identified, or aggregate, data should be used whenever possible unless it will not achieve the defined purpose.
Couldn't we take the same approach of necessity and proportionality writ large when it comes to voluntariness as well?