The op shop might know the verbiage spelled out by the warranty from the oem. If it is so, the shop's weak point is not understanding that customers don't know the coverage nor understand what to expect.
The outcome is a dissatisfied customer and the follow on impact is negative reputation.
If anything, the takeaway is that the shop needs to be responsible in being upfront to disclose the potentials that the customer may be obligated regarding any financial impacts.
Poor communication and lack of due diligence on both parties.