Here's a thread I started yesterday (?) asking about the same topic. https://productioncommunity.publicmobile.ca/t5/Get-Support/Do-PM-subscription-charges-go-through-CC-...
My CC is 3% on recurring (& gas & groceries) and 1% default. My PM went through at 1% (years ago) so I switched to a different card that gives me 1.5% on everything. I have on occasion bought a PM top-up voucher at Loblaws or wherever (to get 3% as groceries) but it's more work and I decided not worth it for only an extra 1.5%. In the other thread, someone mentioned a card that gives 5% at 7-11, now THAT might be worth buying a voucher (especially with the newish "instant top-up"). See other thread for details.
I'm quite sure it's on PM, every merchant has a merchant code (some more than 1) identifying the category. The cashback is tied to that code, and sometimes you just have to try and see. It's not always obvious, e.g. is Giant Tiger or some independent greengrocer considered groceries on the CC?, and what about Wal-Mart (the answer used to be: there are 2 kinds of WM in Canada, and 2 kinds of CC; 1 of the 4 combinations went through as groceries/supermarket, the other 3 of the 4 didn't). PM could probably change their merchant code if they wanted, but there's no incentive to them.
