I've never seen a thief so blatant as to jimmy open a trunk.

That's how my first CD player was stolen. They used a crowbar on the rear hatch of my GTI. The repair was rather expensive because of the significant damage they caused.

With my second theft, from the same GTI, they were more clever and broke a front window. Then they climbed into the rear seat and lowered it so that they could get into the trunk area without opening the rear trunk. They were able to pull the subwoofer out of the trunk that way.