I know we are on this planet for way too few years, but in the grand scheme of things are we really so time conscious that we don't spare a few seconds [which is what we are talking about here] to maintain politeness? The lounge ladies have to keep their wits about them for all sorts of reasons and it's not unreasonable to give her (or indeed him) the courtesy of our attention briefly.

Sure, if you are waved back in that's fine. Otherwise, well, it's part of being British surely?