The timber harvesting rules in Canada are not more lax than in the US, if anything in recent years they have become extremely tight. The styles of logging, especially on the west coast, have become restrictive to the point that they can't make money selling lumber anymore since the cost of raw logs is brutal. I have some great pictures of helicopters plucking logs off of hillsides so they don't have to put roads or clearcut areas.... you can't tell me plucking logs in 2's and 3's with a helicopter doesn't cost some major $$.
The biggest reason for cheap Canadian lumber is that everything in Canada done to cut the trees is paid for in CDN bucks which hold only 63% of the value of a US greenback. That makes our logs cheap. It also makes most other Canadian exports (paper, minerals, oil, etc) all cheap too but that doesn't stop the US from importing those.
Grew up in a logging town, with saw mills, and paper mills producing products from tree chips. US tariffs have put a lot of people out of work even in what used to be my small neck of the woods. A lot of medium sized communities have all but dissappeared. It'll only get worse too, know people who have been to mills in some 3rd world places, no environmental considerations there, and they produce stuff even cheaper.
-Soda
The Assassins.