MREInfo.com

The risk is simply very small, there canadian, US and european livestock regulations are about the same.. very strict.
But.. there is always a risk (especially from Europe, lots of cattle very close to eachother; risk for epidemics.. and the epidemics mostly show up to late)

But it's probably due to "protecting" of American livestock companies. You could completely flush away the American market when you would allow south American beef on the market. (Also strict health rules in Brazil and Argentinia)

And if you allow canadian and european (expensive..) meats.. you just have to allow the brazilian and argentine meat aswell.. so I think it's simply a covered up way to add to the price of south american meats (import tax, health certificates, lots of paperwork..) and protecting their own markets..

When speaking of the difficulties in shipping in/out of the country you need to be aware that the regulations are written with the needs of commerce in mind. The regulations are not intended to facilitate individuals shipping occasional small quantities. Regulations that facilitate the safe shipment of truckloads of goods across borders are bound to be a bit much for small packages, but disease does need truckloads to spread.

I once had to ship a show dog to the UK, they required a six month quarantine( that was before the PETS program) to enter the country. Obviously, there are not that many dogs being shipped but England seriously intends to remain free of rabies.

The operative point is that these trade restrictions, when applied to small shipments, are a barrier to disease and pestilence. The Beef Growers Council of America isn't sweating the economic consequences of someone's Aunt Martha in Quebec sending them a pound of brisket.