It looks like there's something like Black Hat Information Architecture, that is implementing an on purpose bad IA to cheat on your user, and gain some money playing on your user distraction or misunderstanding of the rules.

You probably know Ryan Air a low cost airline operating mainly in Europe, as quite all low cost airlines (depending on the Country they operate/advertise, as in some place now things are changing) they advertise flight at extremely low prices (as low as 0.1 Euro) without putting too much emphasis on the airport/security/fuel surcharge. The resulting fare might rise to tens or hundreds of Euros even if the starting (read advertised) price is just cents. We are no dummy anynore, and already know the trick. That's fine.