But of course carriers wouldn't want that, not only because it would make consumers painfully aware of how much their calls cost, but also because they are profiting from these scams.
Why? Who does that benefit? It's pretty common for phone plans in both the US and Canada to treat the US/Canada as a single region for the purpose of long distance calls and texts.
Its not just "kick everyone out of the US country code", it's protect consumers by principle of least surprise sorta. But again, this only protects against toll fraud and not all of the other "Appear to be in a nation you aren't" scams.