Originally Posted by
minnyfly
Back to this post. Either you've been incredibly fortunate in those 20+ years flying of not seeing any carrier without that effort besides the modern UA, or you're not telling the whole truth. In my much more limited flying experience, I have seen flights not held on every airline I've seen operate. I've been left behind by some of them. It's not hard to see it happen either. You can watch it while killing time at a hub airport.
Even in the last few years I've seen UA re-open the door multiple times. On one flight (I don't recall exactly, probably IAD-LAX) they reopened three times - twice for late connecting pax, once (the last one) to hand in the passport of someone who had dropped it between security and boarding. It probably depends a lot on the time of day, demand for gates, GA, and crew.