Well, i think the point why noone escaped alive from Alcatraz is not that it was harsh or nice. It is a bloody rock surrounded by bloody water. You could give the people inside Playstations, beer and pool billard…. it would not change their chances to escape.
Janus, i think you are mixing up correlation and cause.
No, Falk, Im not. If you put them on the island without such harsh conditions (visit the prison, and youll see the security was pretty damn tight. even still, I would argue that it could stand to be much harsher) they could escape. It is an island, obviously to contribute to the difficulty of escape, but you can swim from their to shore if you are in decent shape, and many people in prison are physically fit.
Take for example, that prison I mentioned earlier in French Guiana. There were prisons on islands, but the main facility was on the mainland. There were extremely harsh conditions there, particularly in solitary, like i mentioned, and there were almost no escapes. The one guy who was reported to have escaped (Papillon, he wrote a book), only managed to because of the apathetic guards.