parabellum - Whilst USA orientated pilots will scoff at the possibility of the RJ crew notifying GMC that they were not clear of the taxiway, in a very large number of places outside the USA that would have been SOP.
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We don't 'scoff' at it. It's SOP in the U.S. also.
But ultimately it doesn't matter if the RJ forget to advise ground control that they weren't clear, or couldn't because of frequency congestation. You(we) are ultimately responsible for the safety of your(our) aircraft. No one else is.