Many Thug Bosses are currently serving a life sentence in prison.
The Thugs want to expand their empire and bring back their inprisoned leaders.
Breaking into prison isn't any regular ordeal, Thugs must own at least a class 2 or higher weapon in their inventory to attempt a prison break, along with 2000 $BILLS. Thugs will always prioritize searching for one of their leaders, although sometimes they must settle for one of their fellow Thugs. Don't be discouraged though, one more Thug out of jail is better than one more Thug back in jail.
On the other hand, Cops may apply to work at the prison, with the requirements being a class 2 or higher weapon owned. They are compensated for each time a Thug is caught attempting a prison break.