Something you have to keep in mind is that there are two parallel markets over there: SV caliber developers and the rest. The former won't have any issue getting a job in the US (takes maybe a week for a talented engineer to get one). Therefore, comp has to be priced appropriately. The later can't -and likely won't ever be able to- secure a US visa, mostly due to skills. A lot of them are immigrants to Canada themselves (there's a reason they immigrated to Canada, it's way easier and the quotas are close to 10x per capita compared to the US). Some companies leverage this and have floors of international devs they park in Canada for a fraction of their US counterpart through a subsidiary.
For software developers your comment is correct. If you’re a Canadian citizen and a professional engineer all you need to get a TN visa is a job offer. There is a path to get both citizenship and a professional engineering title for foreign engineers so eventually the engineers with an engineering degree can make it to the US.
