Don't ask Don't tell...this time current salary?

Recently visited NYC for a mini-reunion with school friends. One of them is a MD, one Research Professor, while the other two are bankers at Citi. Happy to know that banks are investing heavily in ML in both adoption and adeption. Though they don't see ML or valley as an existential threat, yet. I also see a lot buzz at the Canadian banks, hiring data scientists in masses. Many data scientists are PhDs with an interest or heavy weight academics. The unicorn in this case is someone who understands and marries business with machine learning.

One thing my friends were all excited about is that it is now illegal in NYC to ask about the salary history during the hiring process since October 31, 2017. I'm surprised that Ontario labour laws lag behind on this question. Not only employers and especially recruiters ask this question but the latter seem insistent on it. They also seem curious on the demographics of the applicant's residency. While the previous salary may definitely play a role in low balling, demographics seem more subtle in lowering salary expectations. My comment on this is top talent merits top dollars, or employers risk flight of talent.