Anecdotally, I've had the same experience. Interac money transfers from person to person on the other hand is very common

For individual developers it seems useful.

Right now for $1.50 or a monthly fee of $10.00 I can send an unlimited amount of money to a Canadian bank account holder. This would allow Canadians to pay Americans through their bank account.

But I made the comment really to highlight how forgotten Canada is even when it is remembered.

I did once use Interac for an online purchase. It was because the merchant required a "Verified by Mastercard" or some such which was impossible for me to get on my Canadian credit card without a Canadian address (I live overseas). It is a bit of an edge case, I admit, and I would still choose the credit card over the debit card most of the time, but it is once example where accepting Interac was a good thing for the consumer. Of course, I would have been happier if they just accepted my credit card without the "Verified by Mastercard" BS.

I used to pay for prepaid phone credit from Fido's website using Interac online payment. One time Fido's server failed right after the Interac server accepted my payment. As far as my bank could tell everything went through fine, but Fido had no record of any attempt at payment. I only use my credit card online now.