If people could buy tickets and season tickets willy-nilly, there'd be big trouble. Any fan of any club could go, cause trouble, or even more! At least this way, they know who is coming to games, and can track them down if they are trouble makers. (This is partly how Genoa managed to ban some of their fans for the way they acted a few weeks back.)
At the end of the day, yes it is frustrating, even more so for International fans, but it promotes their International Membership for sale, of which I will certainly be buying with the money I would have spent on a trip to Rome and tickets for the Coppa Italia final. I'm not missing out again due to the red tape.
In the Premier League, all tickets are available from the club directly, and all names are kept on a database. They will ask for ID and proof of your address, and for big games, you MUST have bought tickets previously, to prove you're a fan of the team, and not just there to kick off.
Juventus must break down this wall. They've already made a giant step in the new stadium. Selling tickets on their website generates not only more traffic, but is also much better and easier than going to Listicket. Also selling tickets at the stadium can continue.
It's not rocket science, and they MUST look into it sooner or later.
If you're in Turin, it'll be on EVERYWHERE. That much I'd be sure of!