Postal worker checking in…
Okay, an Australian one, so I can’t comment on the Canadian situation, but I can give you a general overview of how it works, and how it works is thusly:
Postal administrations tend to treat incoming ex-overseas mail like dirt. To adapt the Australian experience to what I assume also goes on in Canada, it will work along the following lines: let’s say you have a sorting centre based in, say, Calgary. It will be responsible for reciept of mail from the various Calgary post offices, which it then sends out across the country and across the world. It will also be responsible for incoming mail for Calgary addresses. So, let’s look at the incoming stuff. It’s a busy night at the Calgary Mail Centre, and the place is humming. There are several hundred thousand letters “on hand”, waiting to be fed through the sorting machines. These are local, national, and international in origin. The duty manager has to prioritise this stuff, so he makes his pick of what to feed through first. This will invariably be what we (Australia Post) call “own to own”. That is, mail posted IN Calgary FOR Calgary. If that mail is delayed, then not only does Canada Post look bad generally, but the Calgary Mail Centre will look bad specifically, and it is that particular manager’s arse (bonuses etc) on the line. There is nowhere else that the mail has been - nobody else to blame. Next priority is domestic Canadian mail generally. If that’s late Canada Post still looks bad, but the manager can blame “those slack bastards in Toronto”. Finally, comes international mail, where you can shunt the blame over onto an entire different administration. A Canadian postal customer regularly receiving US mail late will invariably blame the USPS because “Hey, the local stuff gets here on time” (and of course it does, for the reasons given).
When postal administrations abuse this too much, it is not uncommon for the sending administration to send an arse-kicking delegation over, and then for a few weeks or months things improve. Then it gets slack again.
On the other hand, international mail can be quite quick when it wants to be. A letter from NYC to Toronto will be on a direct flight, and will go post office > mail centre > mail centre > post office. On the other hand, a letter from Buttfuck Nevada to Lower Buttfuck, North Carolina, might have to be handled many more times, even though it is domestic.