I hope all the lbs apologists see this one....

Yes, it's a mech leverage thing. Road BB7s are designed for short-pull levers--- road levers, bmx levers, canti-levers. MTB BB7s are designed for long-pull levers, such as (obviously) mtb levers designed for linear-pull brakes ("v-brakes") or the typical cable-actuated discs.

Your LBS owes you some standard BB7s and an install. Don't settle for less. Crooks like that oughta face criminal charges.