Interesting! I have often discussed this same issue with my similar age children. "No problem" strikes me as the ultimate passive-aggressive response if in response to a service which I am paying for. If "you're welcome" is so distasteful, a cheery "my pleasure" has to be better than "no problem."

Canadians emphatically no longer trust the US as a reliable responsible partner. We will nurture other relationships while our relationship with the US will be entirely transactional.

Welcome home! Looking forward to your presentation tomorrow!