Why each team does this:

Chicago

The Bulls get younger swapping Caruso for Mitchell and pickup draft compensation. Davion can take on Caruso's role and a change of scenery might be nice. Tobias Harris fits this team a lot better than DeMar and they also get draft compensation for taking on the salary.

Kings

Caruso is a championship-piece. His experience and skill would elevate this Kings team in the playoffs, and his fit with Fox Sabonis Murray and Huerter is perfect to be the perimeter defender Mitchell never could be.

76ers

This might seem a bit rich for a player swap, but the reason the 76ers do this is not just because DeMar fits well there: they also create a 10 mil trade exception, which would be used to add a second star.