i've never seen this in Canada but even in the U.S., I don't think it's being misused the way that people are suggesting here.

I have referred thousands of callers to TheWorkNumber (and competitors like 'Thomas and Company') in my years working at a call centre and the reason is always the same: income verification for somebody who needs to get approved for a mortgage loan application or something else like that.

I don't actually see any suggestion that the salary data is being "sold" per se rather than just being used for legitimate income verification purposes