I just ran across a Canadian home baker who is shipping cookies all over the US. She has a website, a Facebook page and a shop on Etsy.

It depends on the laws in her province and whether or not she is complying with the applicable export regulations listed here:
http://www.tradecommissioner.gc.ca/eng/exporting-to-united-states.jsp

If I had to guess, I'd answer "a lot".

It's illegal to have a home bakery in my province, yet I constantly see people advertising their home bakery all over Facebook, and they have websites too. It's really frustrating!

It's not even a province wide rule it depends on your municipality. My area, I need to have a completely separate kitchen in my home in order to run a home bakery, so if this person has that she could be licensed.

There are a lot of people on Etsy who sell edibles like cookies, but I doubt they're complying with the FDA regulations. As far as shipping from Canada to the US, I'm sure there's more than a few things wrong with that.