Re: And I love the ones in the UK.
From Wiki: "Passenger services were reported as "to end on 31 January 2016",[15] although British Airways/Sun-Air continued temporarily to operate flights from Cambridge to Gothenburg. Since 24 March 2016 tickets have not been available to the general public.[16] As of November 2017 the flights now originate in Manchester with a brief stop in Cambridge."
Sure it's International. Just not quite as much as the OP's "flight to Canada or Mexico" which are probably ongoing, regular weekly passenger services (or will be again, post-Covid).
Note that the "International" designation gives certain benefits, tax-wise and etc. I don't know about you, but if I ran an airport I'd certainly take advantage of all the financial incentives that I was legally capable of getting. If adding "international" to the name gives me more, hand me a bucket of paint!
Biting the hand that feeds IT
