If the Barca game (or any other Euro away) goes to general sale, then there will be no need for checks as anyone who wanted a ticket will have got one.
I don't really see why those who went to Bucharest had to collect. Seems to me that the system should only be used for sell outs, and then perhaps require 10% to collect.
But if it were that simple, I cant see why the club haven't introduced a better system. This process must be a right hassle for them. None of the theories that have been put forward as to why they want all of that hassle (eg to encourage fans to go on official trips) seem to me to stack up.