It's not discrimination if that is the treatment doled out to every he/she/them that behaved similarly. Personally I would go for a shoulder punch as the approved physical lesson instead of a slap as it is much less personal but has similar effect. Give the person having that tantrum the choice of conventional or summary justice prior to doling it out. Body camera records the situation so it isn't abused.It's all about efficiency. Why waste the time of cops, prosecutors, defence lawyers, judges, prison guards, etc when a solid slap could bring about the same result? If she did this a few times and was slapped each time then she'd soon be a bit more fastidious about being on time for something as important as a flight. Too many resources wasted for a glorified school yard fight.
And there's a lot of cry baby husbands that deserve one upside the head too, no need to be sexist