While technically true, f.ex. Finland has stopped all mail shipments[0]. I guess the airlines were not set up to dealing with the hassle of making sure all the shipments are “allowed”. Or maybe just lazy, dunno really.

[0] https://www.posti.fi/en/latest-news-at-posti/%20/news/trump-...

Thailand too: https://www.reddit.com/r/Thailand/comments/1mx1m9r/no_mail_s...