"Like I said it's bad deal for everyone involved. It's not fair to you nor the shop owner."
Fair doesn't enter into this. It's what is right. If someone brought a piece of machinery, tractor, truck, ATV, whatever to my shop for repairs I would be responsible for it's safe keeping until you get it back. It's very unfortunate for the shop owner to have to take money out of his pocket if he doesn't carry insurance for unforseen issues. If he's a legitimate shop, as opposed to a private guy working at home, I would think he would have liability insurance. Either way he should be held accountable.