The explanation is simple.
The Pep Boys change was handled by a freckly kid making $5.50 per hour, and was told "Ever change a tire boy? You're hired, go try that X5 in the parking lot". You are lucky the rim wasn't scratched.

BMW pays probably $25-$40 (or more?) per hour to the mechanics and sends them to weeks of training on very expensive equipment before they touch a car. They then have a single priced hourly rate and fixed time estimates designed to cover the most complex job, not just simple tire changes.

I don't like the BMW rates but I understand it and just paid it to install my spare tire kit. Something I could have spent a Saturday afternoon on.

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Richard
Sir Snaps-a-lot, 9 Time Dragon Slayer (54 runs!)
2011 X5 50i Alpine White, Biege Nappa /Lt Poplar M Sport
2009 Z4 35i, Black Sapphire/Ivory-Black/Anthracite

Gone but not forgotten: '08 550i, '06 X3, '06 650i, '02 M5, '99 540i