I've seen this happen on countless cruises and in everyday life, but I never usually say anything as most people don't either. Being brought up in a family of 9 children, manners and respect come first; no if's and's or but's. And if you did get out of line, it was your "butt" that got it!!!!! ouch
Next month I'm taking my mom on her first cruise for her 80th birthday. And while she can walk, ships are big, so I will bring on a wheelchair for her so that she won't get too tired. If any of those SOB's try to rush in ahead, I promise I will not be tolerant. The older I get the more vocal I get also.
I'm with FirstCoast in that I would take the stairs before I snagged an elevator before others who really needed it.