nobody could complain that the government gives money to rich people buying expensive cars.
Instead, people would complain that the government makes systems that only rich people can work around, since the taxes would target affordable gas vehicles and you can skirt them by buying a Tesla.
In general, the fact of the matter is that most Canadians believe that the taxes should heavily tax the wealthy in order to provide essential services (medicine, education, etc.) and that the rich are most likely avoiding those taxes with complex schemes that the average person can't understand.
The top 1% income earners altogether account for 11% of all income earned in Canada, and pay 22% of all taxes collected (
source). About 6,000 Canadians in this bracket avoided paying any tax at all, but they are a small portion of this 11% of all Canadian income earned (
source). William Watson tries to make the case for high income earners getting some respect/thanks for their contribution to the tax pie, but I suspect
his message doesn't generally resonate, though the graphic provided is good.
Bottom line: on your $148,500 CAD Tesla, you'd pay $19,000+ in HST alone, enough to cover the entire cost of your own rebate. In other words, on a Tesla, your government "rebate" isn't the government giving you someone else's money, it's them giving you back your own money. On your $36,000 Nissan leaf, your HST would cover only about $4,500 of your incentive, leaving the government the need to find about $10,000 of other people's money to fund your purchase.
However such arguments are very unpopular, because the mere fact that you can afford a Tesla means you're in the top 1% and deserve to pay other people's rebates, but not your own.