I suspect you'd find it's common in most English-speaking non-USA metric-embracing nation states.

It works fine spoken, too, because we could say 'imperial ton' or 'american ton' if we ever needed to refer to a specific, archaic, mostly abandoned unit of weight - which is, rounded down, effectively never.

FWIW we're taught to pronounce the word somewhere between 'ton' and 'tone', but, really, the context here is that all tonnes (or phonetic equivalent) are metric once you're outside the USA.

Re-purposing words - even 'only works in writing' (like we're using to communicate here) words - seems whatever the opposite of 'luxuriating in the massive potential breadth of language' might be called.

Specifically 'metric ton' I expect would be mildly offensive to everyone that uses metric, and doesn't want to disambiguate the pre-existing, and clearly more widely prevailing homophone of 'tonne'.