I suppose that's a matter of opinion really. Phantom Thieves are generally a person or group of people who want to bring about reform somehow. They tend to steal things for a specific reason as a way to generally do something good. Although the stories I've come across very, there's some sort of common goal. They go about their objective in secrecy to expose wrongdoings at a later time. Calling cards seem to be a common thing, warning the target it will happen prior to or sometimes after the fact.

The Phantom Thieves I'm familiar with tend to send a calling card prior to stealing their "treasure". Their goal is to reform a corrupt society and make the world a better place, but despite how noble their intentions tend to be, it makes it no less than a crime in the end.

Needless to say, the leader has been arrested twice at this point. And yet he seems to be the savior that everyone has learned to look up to.

[Sometimes. Public opinion was fickle on occasion.]

It's intriguing, is it not? Perhaps it's a rite of passage for a hero to serve jail time for trying to do the right thing?