Not necessary. The GST in Canada is quite hiong compared to Singapore. It consist of a federal tax component (7%) and a provincial tax component (7% to 10%). For tourist, you can only claim the federal tax component (7%).
In every major city, there is at least one good photography shop, but the problem is finding them (provided you know their roads well) . They have a wider range of assessories than shops in Singapore, but are a pale comparison to Japan's. In Japan, filters alone can fill up a few racks, and they are not behind counters; they even have a basement selling other non-camera assessories like dry boxes, blowers and brushes.
In Canada, except for the shop owner, most over-the-counter-salesperson don't really have good product knowledge. Again, the knowledge and service simply cannot match Japan's.
But of course, staying or touring in Japan is very expensive.
I can only compare these 2 countries cos I don't have any experiences with other countries.