yep, and because if they seriously stuff something up, then have insurance to cover it etc .... oh, plus they issue a tax invoice including GST, which I can claim for my business expenses.
But I wish I didn't have to get things done professionally, as
1). EVERY single workshop (except GT Autosound) have ripped me off to the hilt ($70-$90 per hour is RIDICULOUS!!), and
2). Most of them don't actually do good quality work (again GT Autosound excepted) - and most don't give a crap about you or your car, they are interested in getting your job done and the next one in the door.
My 2c