Hi Frank,
Since I work for a bank I can provide a slight insight into the US banking system. Part of the issue is that banks have different regulations governing them depending on their charters - federal or state, commercial bank, mutual bank, community bank, or credit union.
Most commercial banks (Citibank, Bank of America, Citizen's Bank, etc) should be able to provide money orders and treasurer's checks in foreign currencies. They should also be able to accept checks in foreign currency denominations and from foreign banks. The latter is easiest if the check is in US funds payable from a bank with a reciprocal relationship with a US bank (often in New York). This is actually quite common for Canadian banks, to issue checks in US funds payable through a New York bank. Of course, there are usually fees associated with many of these services.
The US Post Office, for whatever reason, only deals in/with US currency and the 48 continental states.
For non-commercial banks, they are more limited in what they can accept and what they can issue. We can accept certain kinds of foreign checks, but can't issue any monetary instruments in foreign denominations. Some financial institutions, even if their charter allows it, may choose not to work with foreign items at all, in large part because it incurs signicant expenses and staffing requirements. A simple call or visit to the appropriate financial institution should be able to clarify the policy - of course I say that as an employee of a bank with good customer service.
In short, your feeling that it is "hit or miss" with US banks is not far off the mark. Despite the fees involved, my recommendation is really the wire transfer (at least for larger amounts). My sister attends McGill University in Montreal, and that's the best way we've found to consistently get her money.
