Firstly Canada produces about 1.5% of worldwide GHG. A small number of EVs will make little to no difference. Canada contribution to GHG has been declining on a per capita has been gong down since the 1990s.

"The level of emissions per unit of gross domestic product was 33% lower in 2015 than in 1990. Over that period, GHGs per unit of gross domestic product decreased from 0.62 megatonnes (Mt) of carbon dioxide equivalent (CO2 eq) per $billion gross domestic productFootnote 1 in 1990 to 0.41 Mt CO2 eq per $billion gross domestic product in 2015. The amount of GHGs emitted per person in Canada decreased to 20.1 tonnes CO2 eq in 2015, compared with 22.1 tonnes CO2 eq in 1990."

https://www.ec.gc.ca/indicateurs-indicators/default.asp?lang=en&n=79BA5699-1

Massively subsidizing and industry that really can't survive on its own merits is foolish. Giving buyers of a Tesla, a car not made in Canada means that other programs are starved for funds.