[benzor]

As a native French speaker from Quebec, I can tell you it's much more common in France, so if you went to school in North America that might explain it.

[umanwizard]

In the US, french from France is taught. The Quebec dialect is barely mentioned.

Btw, in France, “si” in that context is not just common, but absolutely required. People would be confused if someone used “oui”.