Cheap Gas along 401

there is cheap gas in two locations near sarnia(across from port huron mich)

just south of the city on hwy 40, 15 minutes from the us/can bridge

north east of the city towards grandbend on hwy 21, 30 minutes from the bridge

no id required

We often pull off at exit 566, Marysville, drive south a few kms and fill up at Speedway . Usually save 8 cents a litre or so. No issues. Everyone gets the cheaper price. No ID card needed.

Same situation here. I fuel up on the reserve (if I can get to the pump it is very busy) for convenience but price is the same as in town.

AFAIK, unless you have a government issued "indigenous person" id, you pay the going area price for whatever you buy. Only the aboriginals get the cheaper price/rate.
That may have changed, but that's how it worked a few years ago. Used to live and drive near the Brantford 6 Nations area when we lived nearer to it, and pulled in once, only to find that we didn't qualify for the much lower price displayed on their price signage.
Maybe some of the on reserve stations (Mohawks?) don't care any more, and sell it to everyone now?
Got a Costco card? There must be a few along your route, and they're probably the cheapest, just off the 401.

Official government blah blah
https://www.fin.gov.on.ca/en/bulletins/gt/3_2011.html