My DW and I each try to have about $200CAN on us when we travel in Canada; as others have pointed out the systems go down sometimes and cash is the only way to pay for things. And you may stop at a farmers market or buy some fish, etc at a roadside stand. Last year we purchased some scallops from a young man selling out of the back of his pickup near Kitimat BC, they were super fresh and tasted wonderful. And we feel safer in Canada than many places in the US from pickpockets or muggers, so having cash on yourself is no problem.