Do "Pay-As-You-Go" Phones still exist?

This seems like it would be easy to find or answer, but I can't seem to find a simple "pay as you go" phone. I want to buy one (or a sim card) in Vancouver, and only local calls will be needed.

To be 100% clear: this is not a "monthly plan with no contract". "Pay as you Go" means that I, for example, pay up front for 30 minutes of calling, and I would not get charged again, and those 30 minutes would not "expire" until they are actually used.

It seems like at some point "pay as you go" morphed into monthly plans that don't come with a contract.

Background: I am trying to get an "emergency phone" for my kids, so I just want to know that they can call me if needed, but not have a new monthly charge for something that will never get used. This used to be super common, but now when I search "pay-as-you-go" they are just monthly plans with no contract.

Thanks!