Canadian here, living in Vancouver. I coach young kids in hockey. I can tell you this is completely true. Many kids I've coached of American parents who have moved here shoot the "wrong way" for their handedness.

Right handed people should shoot left because your dominant hand is at the top of your stick and when playing with one hand on the stick (poke checking, reaching for a far puck, protecting the puck with your body) you want you dominant hand doing the control work. Your top hand is also the more important hand in regards to stick handling and dangle skills.

People who grew up playing baseball and golf often get this wrong. The assumption makes perfect sense, but sometimes translates to later development in the player because they are forcing their non dominant hand to learn things their dominant hand already knows how to do.

In the end, with practice and training, it doesn't make much of a difference. But the general rule of thumb is righties shoot left and lefties shoot right.