Is it random? I imagine they are not kicking a Global Services passenger off because they got RNG'ed.

Most likely the lowest fare ticket on the plane, since compensation is capped at 4x the cost of the segment.

They never said random, they said a computer chose who to bump, probably like this:

    select name from passengers order by ticket_price desc limit 4;

I get the feeling a lawyer will want to see that "program"'s source code. I also get the feeling that will be some interesting moments in court.

And probably eliminates everyone flying with multiple people on the same reservation.

The article mentions the first two people asked to leave were a couple flying together.

Oh, interesting. I just kept picturing them requesting a child to leave on their own, or some other insanity.

A couple were asked to leave first. Maybe for reservations of >4?