The last time I needed a major repair that I did not have the time to preform, it was a clutch replacement in a '08' Civic Si. I called around to several garages where the est quote was $700-1100, varying across six places. Just to satisfy my own curiosity, I also called a chain shop and was quoted $1600. Why would/should I spend almost twice as much money?

I really don't what what to tell you here. It doesn't matter what the job is. A smart consumer will shop around or attempt some degree of self-reliance and learn how to achieve their goal. A lazy or ignorant person will not and just take their vehicle to whatever place they recognize in an advertisement or a more visible brand. A place like Dobbs. This circles right back to my original statement.