I've actually been friends with people over the years who have had experiences like this. Canada likes tourists, it just wants them to actually be tourists. We don't want you to 'visit' and then attempt to 'stay' or then attempt to immigrate. That's something you apply for and do the paperwork for BEFORE entering Canada. So some of the situations I've been privy too...
CBSA: "Reason for entering Canada today?"
Person: "Imma moving to Canada to live with my internet girlfriend forever and ever! :3"
CBSA: "Do you have your immigration forms with you?"
Person: "What are those?"
CBSA: "So, we're gonna put you back on the next plane to the United States now."
CBSA: "Reason for entering Canada today?"
Person: "I'm a Canadian citizen, I've spent the last six months living with my American girlfriend in the United States but my time has run out. Now we're coming to Canada and we'll figure out the immigration thing while visiting."
CBSA: "And you're bringing a U-Haul with all of this American's worldly possessions and even towing their car behind it?"
Person: "...Yes?"
CBSA: "So, only one of you can enter Canada today, the other gets to drive back to Arizona. Guess which one is which."
And watching more of this show, it seems a lot of people put no thought or effort into immigration, not even illegal immigration, they just think they can show up in Canada and 'figure it out' while 'visiting'.