There's a big difference between shop rate and mechanics wages, just as there's a big difference between what hospitals charge and RN wages.

If shops paid mechanics everything they charged you, they'd go out of business in a month. Just as if hospitals paid everything they charge to their RNs, they too would go broke.

You can't compare billing rates on one side with wages paid on the other. It's like thinking migrant laborers get the full benefit of that 59¢ a can you pay for tomatoes at the store. Hell, if I got paid 59¢ a can to pick tomatoes, I'd quit my job with the city in a heartbeat.

For the record, shop rate around here, Land of Taxes, is $65 to $70. Starting mechanics make about $10-$12.