Something like Guantanamo doesn't happen because two people dream it up. It happens because a gigantic organization is committed to it.

It also wouldn't have happened unless there was solid political support at the highest levels. That includes not only politicians but the parts of a democratic society that isn't necessarily directly elected, within the justice system, military and media.

The system also has been held up under multiple administrations, including one that probed public opinion enough to debate closing it only to turn around and expand it instead, which didn't make a measurable difference with voters. The last part is the key point here.

All this may sound a bit hopeless, but we know how to fix these types of inherent issues in a society, by proper application of division of power.