Pretty sure restaurants and car mechanics aren't unique skills and when they retire in my area someone usually buys them out and continues operating under the same name...
From what I recall from reading one of the "E-myth" books a while ago, whether the newly-owned shop will operate similarly to the old one, and also how difficult was it for the original owners to sell it, will depend on the documentation GP mentioned.
Going from my memory, "E-myth" book(s) insist on thoroughly documenting operating procedures and turning them into playbook. Rigid in terms of personnel training, but open to change if someone figures out an improvement. The goal is to be able to scale up operations into multiple venues (franchise models) while maintaining highly consistent appearance and level of quality.
As much as having such documentation will make it easier for a franchisee to get the business running (the books call it "turn-key business", IIRC), it will also make it easier for a potential buyer to take over and immediately hit the ground running.
The properties already converted for specific use, so it is cheaper to reuse as much as possible.
But those will be different businesses. The restaurant will not make the same dishes or retain the same customers. The mechanic will operate on different types of vehicles.
