In Canada though? Because in Canada it is definitely rare to see cash now except in boomers. Even a lot of places don't accept cash like gyms for even purchases like drinks or towels.

If you frequent small (generally Asian) restaurants, it's quite common to see signs saying they only accept cash in Vancouver. Otherwise, if they take credit, they may attempt to incentivize paying with cash via discounts.

Same, here in Toronto. My favourite Asian fruit market only takes cash, and a lot of the corner stores have a minimum purchase for cards.

But any business with any sort of margin (as in, I’m not buying grapes for 99¢/pound) takes contactless payments. My gym would look at me like I’m crazy if I tried to pay with cash, and Billy Bishop airport has been cash-free for years.

Why is that? What's some advantages of having a credit card versus a debit one?

Customer protection- credit cards allow you to reverse charges on defective or fraudulent purchases if you are unable to find recourse with the vendor. They usually side with the cardholder as long as a basic paper trail of a good faith attempt to resolve the issue with the vendor is included.

Also, credit cards often include insurance on purchases. For example, one of my cards will reimburse my hotel/car rental/plane tickets in certain cases of trip interruption if I purchase those items on that card.

There are similar protections on debit cards/chequing accounts here in Canada thanks to our strictly regulated banking system.

Failure condition - your conceptual exposure and, at least in the US, legal exposure is more favorable in the face of fraud.

Would you rather have someone thieve a dollar from your wallet or fraudulently assign you a debt?

Ignoring the obvious one that you can pay for things you don't currently have enough money for (bad idea in general), I pay for almost everything on a visa card for travel points.