You'd be thinking wrong. Canon cameras also use the IMG_ format. It's been a while since I've dealt with GoPros, but I'm pretty sure they are IMG_ as well.
While it's nice to hold onto what you know from experience, extrapolating that to end-all-be-all knowledge is just not a good stance. Especially in the light of information from people with wider breadth of information.
That's a sweeping statement that is definitely not true for all cameras Canon has made.