When I was much younger I was sent 'onsite' regularly to set up machinery that had been made by the company I worked for. This is still pretty common in anything related to industry because you're just simply not going to be able to train a local to troubleshoot/install a machine that they have no clue about. Some of this stuff takes years to become familiar with.

Experts setting up machines are not “labour.”

At a former US job of mine, for a US headquartered company, I (a US citizen) was told similarly for my trips to Canada. I don't think it was by HR or legal though, it was either an older team member or one of the managers. But they reiterated that when I would occasionally travel to our Canadian office where half my team was, I should say I was there for meetings and I was not managing anyone. (I don't know what our team's manager said if they asked on the latter bit.) The primary purpose was of course meetings (and meeting artifacts), and it was never longer than a week, though my layman understanding would still call that "work", and in any case I'd have my work-issued general purpose computer with me. But this phrasing is all just to get past border control with minimum fuss and just my passport (card). I highly doubt in this particular post's case the problem is a "language issue".

On a conference trip to Italy, they basically asked me nothing. "Where are you going? Ok, next." Hardly any security either. You even had to walk through a gift shop to get to the customs area. It was nice.

Almost everyone I know who goes to the USA for “business meetings” on a b-1 actually works while in the US whether it be coding, report writing, consulting for money, professional services, etc…

That’s for me to know and you to wonder.

Trust me, no one in my role thought travelling once a quarter through EWR was a privilege. Haven’t had to visit for ten years and will never have to again, thank goodness.