Why is Immigration Canada not enforcing our Immigration Laws?

Kudos to fellow blogger, SDA for raising this issue in one of her posts.

According to an article in the National Post, 180 Mexican illegal aliens, who were living in Florida have been allowed to enter Canada through the Windsor crossing, by Canadian border guards. Local Canadian agencies that work with refugees have been asked to brace for another 4000 to 8000 more Mexican refugees.

Mexicans pour into Canada from U.S

"Ortega's dream, as he recounted it Tuesday standing outside a room at a Windsor motel, is now but a memory. He is one of an estimated 180 Mexicans from Florida who've rushed across the border and into Windsor to claim refugee status, fleeing a crackdown on illegal aliens in Florida.

Local agencies that work with refugees have been told to brace for 4,000 to 8,000 refugee claimants."
...
"After driving his 1996 Grand Caravan for 24 hours without stopping -- except for gas and food -- the Ortegas arrived at the Windsor tunnel Sept. 11. When they told the border guard they were seeking refugee status, the Ortegas were given a list of social services organizations to contact for support"

The question that I have is why did the Canada border guards not turn these illegal Mexicans aliens back to the United States, as mandated by the Safe Third Country Agreement? Most of them are economic refugees, not facing any harm or persecution in their own home country.

I thought that there was an agreement between the United States and Canada, called The Safe Third Country Agreement that prevented refugees that arrived first in the United States from claiming refugee status in Canada.

Canada-U.S. Safe Third Country Agreement

"Under the Canada-U.S. Safe Third Country Agreement, persons seeking refugee protection must make a claim in the first country they arrive in (United States or Canada), unless they qualify for an exception to the Agreement.

Execptions

• Family member exceptions
• Unaccompanied minors exception
• Document holder exceptions
• Public interest exceptions

From what I see, most of these Mexican refugee claimants would not qualify under any of the above categories, so why are they being let into our country? In our cities, our social services are already strained and stretched beyond capacity.

Immigration Canada needs to step up to the plate and start enforcing our immigration laws, otherwise Canada will soon be facing the same, out of control, illegal immigration problems that exist in US border states, such as California, Arizona and Texas.