For 60 amp in the same building shouldn't he just be able to run 6-3 NM-B, which would provide his 2 hots, 1 neutral and 1 ground?
Just to note in detatched garage NM cable wouldn't be allowed because it is not rated for underground.
I see what you're saying about the ground bar... I ran into the same thing, my garage subpanel is a Homeline 100 amp main breaker load center. You have to buy the ground bar seperately, they give you a multitude of places to install it - it only takes 1 screw and it's located by 2 bumps on the main panel. Real easy. The ground bars can be purchased in various sizes, for me the cost is $4-7 depending on how many screws... I put 2 ground bars in so I could have one on each side so I didn't have to run really long ground conductors around the whole perimeter of the panel.