My own answer to the question is yes, but not directly. As with many other laws it would take a court ruling to definitively spell out how international agreements are applicable to a given situation. Unfortunately it doesn't seem that such a court ruling was ever produced so far:
Google Scholar fails to list any US court cases relevant to the Convention on Road Traffic. The only somewhat relevant case is Busby v. State in which the court rules that one cannot drive in Alaska with an IDP after having been previously restricted from driving in Alaska. The court does stress out that:
The Convention does forbid a signatory country (or subsidiary state) from imposing or enforcing license revocations in a manner that discriminates against residents of other signatory countries. But Busby does not claim that he was the victim of such discrimination. Busby's license was revoked for conduct that would have led to license revocation if committed by an Alaska resident. (Indeed, Busby's license was revoked while he was an Alaska resident.) And Busby does not claim that he was singled out for prosecution because he was a resident of a foreign country—i.e., that the State would not have charged him with the offense of driving with a revoked license if he had still been an Alaska resident.
This could possibly mean that the court believes that the Convention only applies to foreign residents, but its not spelled out specifically.
Searching for Canadian court cases likewise doesn't turn up anything useful. The only relevant case is R. v. Lawend where the person in question was trying to drive in Ontario on a foreign license after previously having had their Ontario license suspended. Here the court rules similar to the decision in Alaska in that having a foreign license does not allow one to circumvent locally imposed license restrictions.
Searching for UK case law doesn't turn up any relevant court cases.
- Australian case law is likewise mute on the subject.
There is also a relevant legal opinion by the Department of State quoted in the Digest of United States practice in International Law, 2002:
Reading these provisions as a whole, we believe that the State
of Georgia, consistent with the CRT,
(1) must permit an alien to
drive in Georgia using a foreign driver’s license issued by a country
party to the CRT only if the alien has been lawfully admitted to
the United States;
(2) must permit a lawfully admitted alien to drive
in Georgia using a foreign driver’s license of a CRT party only
during the first year after the alien’s admission; and
(3) may, in
accordance with Georgia’s residency laws, require an alien resident
in Georgia to obtain a Georgia driver’s license as a condition for
continued authorization to drive. By the same token, nothing in
the CRT would prevent the State of Georgia from applying more
liberal rules with respect to the driving privileges of aliens.
In Automated Vehicles Are Probably Legal in the United States, 2014 the author further analyses how the 1949 Geneva Convention is applicable within the United States. First, to settle the definition of "international traffic":
Nonetheless, the United States ultimately accepted that “the purpose
of chapter II was to establish, in effect, an international code of minimum
safety requirements. By indirection, the rules of the road set
forth in the convention would apply to the pattern of domestic as well
as to international traffic.
The author the meaning behind Article I of the Convention:
Article 1 states in part that no party “shall be required to extend the benefit of the provisions of this Convention to any motor vehicle or trailer, or to any driver
having remained within its territory for a continuous period exceeding
one year.”
This provision, on its face, indicates that the parties recognized
that the treaty would benefit individuals. In no way does this
recognition compel a conclusion that the Convention is self-executing,
but it does suggest that the treaty is of a type that the Senate might
have understood to be directly enforceable.
And finally on the issue of whether or not the treaty is "self-executing":
For these reasons, it is likely that courts will continue to treat the Geneva Convention as self-executing. Nonetheless, a court might conclude
that, with respect to section II’s rules of the road, the governmental obligation is merely to “take appropriate measures”
and that such an obligation is too vague to be enforced judicially.
So it seems absolutely clear that the Convention intended for participating countries to allow foreign drivers to drive abroad for up to one year. However international treaties are not self-executing by default in Canada, unlike the US:
Canada is bound by the terms of treaties that it enters into and breach thereof may give rise to international claims. However, in Canada treaties are not self-executing; they do not constitute part of the law of the land merely by virtue of their conclusion.
So even though British Columbia is violating the 1949 Geneva Convention one cannot directly rely on said international agreement to enforce their rights. But another state party could theorethically sue Canada on behalf of its citizen to request that Canada rectifies its laws with accordance to the agreement.