$5000 for a single electric vehicle is what, 10% or less of purchase price?
$500 for a single electric bike would be 10-50% the purchase price of an electric bike (with $5000 being a high end cargobike).
That's 10x the number of Canadians that can use the funds.
That lowers the floor for Canadians to access the rebate.
That means taking vehicles off the road and reducing road and health liabilities for Canadian cities and provinces.
It is much easier for a bicycle manufacturer to pop up than an entire electric car chain. (Some of the struggling ones might hope the border to become Canadian made).
Yes, this differs replacing gas cars in more rural areas. But it can take the majority of car trips and eliminate then; rather than just electrify them.
It can also position Canada to be a leader in electric bikes, rather than a subsidiary of foreign car companies.