Web searching a bit seems to say that e.g. tourists can use their foreign issued cards and typically carry their issuers' limits with them, unless the merchant has their own limits for some reason.

Putting stricter limits on intermediate devices like pocket computers doesn't seem very tyrannical to me. Interac's web site says the typical default limit would be 2-3000 CAD, i.e. 12-1800 euros or so, unless you have a small business account, then it's more like 25000 CAD.

If you often find yourself spending thousands of CAD on a whim, perhaps it would be a good idea to open accounts with a bank that is tailored to people with a lot of money. I'm sure there are some available in Canada.

I'm not spending thousands of dollars on a whim, but I don't want to wait on hold for 40 minutes to spend thousands of dollars when I need to.