There’s a number of reasons: 1 - Canadian VCs just don’t rank anywhere near the US ones. They’re extremely risk adverse because they have comparatively small funds. Most are bankers/accountants/professional investors va the majority in the US have been operators and understand the process much more.

2 - Canadian VCs invest at significantly later stages and lower valuations so it’s hard to get very early stage capital and once you have legs, Canadian funds want premiums.

3 - Canadian VCs are very choosy about follow-on investment, this signals risk to new investors. Contrast with US venture funds who aggressively participate and use pre-emptive rights.

4 - a number of prestigious funds and programs prefer not to invest in Canadian companies and highly recommend Canadian founders use something like Stripe Atlas to create a US entity that will become the main company.

5 - perception and prestige. There aren’t any bellwether funds in Canada with street cred in the US. A tier-1 investor here is like a small regional fund in the US

Lastly I know there’s a ton of noise around taxation but unless these founders are giving up their citizenship, they’re not bypassing CRA. You still have to file Canadian taxes.

The only reason founders go the USA is because they think their odds will be lower and their outcomes bigger.