I agree you are responsible to a certain extent , if you leave something unattended of that value then yes you are asking for trouble , but if you have a booking at 3am and need to leave after your spot at 4am , boxes in tow , one in each hand , what if someone jumps you on route or at a car park ?
The answer is simple as a community if any of us see a DJ walk to his/her car alone it would be good practice to offer to walk to the car with them ensuring they don't get mugged ..or better still shouldn't a booked DJ have an allocated parking space at the venue ?