As a counter-point, I work for a large national telco and our mass-market site and mobile app (usage in the tens of millions of unique users across all demographics) both use hamburger menus and our internal stats show that almost everyone understands that it's the menu.
I made the cardinal error of speaking broadly from my locale (the US).
My evidence is anecdotal - though repeated - in US fleet/manufacturing/facilities maintenance, and other labor industries.
P.S. I was trying to get in touch with you a few months back, and was unable to find an avenue. Any place I can send an email/PM? Thanks for your time.
As a counter-point, I work for a large national telco and our mass-market site and mobile app (usage in the tens of millions of unique users across all demographics) both use hamburger menus and our internal stats show that almost everyone understands that it's the menu.