I think you might find that the boarding passes issued at Cardiff for a charter flight might well be preprinted cards with little info on them, compared to the scheduled ones the users of this board are used to.

As for their contribution to the gene pool...

I have known an eminent person who flew to Budapest (her choice of destination) when she had meant to attend a conference in Bucharest.

I have also known work colleagues (seasoned travellers) who turned up at LHR to catch flights which were departing from LGW and vice versa, a not too uncommon an occurrence!