It's actually very disorganised and messy in my opinion.
On a recent flight out to Vienna everybody took two bags on board, ie a hold-all/carry-on and a handbag/laptop without any member of staff questioning it.
On the way back, as we queued to board, they announced that only those who had paid extra would be allowed to take two bags on, so I stuffed my handbag into my carry-on, but passengers nearby, who said they hadn't paid extra, just marched on with two bags and nobody queried it.