Lets say there are 50 people in the lowest priority (fare class[0]). It'll pick from random out of these 50 people.

Come'on this is hacker news. I am sure most here have seen the mainframe based applications that entirely control every aspect of airline industry.

These things were coded by professionals over 30 years ago. Its not like these flights are being managed by some buggy wordpress plugin made by some offshore developer.

[0] http://www.cwsi.net/united.htm