Tracks don't mandate equipment, track day organizers do.
Riders Choice, Pro 6, DOCC are organizers who rent out Calabogie, Mosport, Shannonville, etc. They are the ones who set the rules. Anyone who can "organize" a bunch of guys together to pool their money to pay the rental fee can set their own rules and let everyone run the track in flip flops and shorts if they want to. It costs $5300 to rent TMP for a weekday.
I've been to some track days where the organizers let textiles on the track. These are the same ones that allow coolant in the rad instead of water wetter/engine ice, and they also skimped out on marshalls and emergency medical staff. One guy was on the track in high-top leather running shoes. Nobody said anything.
Just because some organizers let you on the track without leathers has nothing to do with the track facility itself. These organizers care only about collecting everyone's entrance fees, not about their participant's safety.
Do yourself a favour and consider your own safety first instead of what trackday organizers will let you get away with.