'Turnkey' is treated as merely signifying the design responsibility as the contractor's.A turnkey contract is typically a construction contract under which a contractor is employed to plan, design and build a project or an infrastructure and do any other necessary development to make it functional or ‘ready to use’ at an agreed price and by a fixed date.
If a contractor builds a "turnkey home" it frames the structure and finish the interior; everything is completed down to the cabinets and carpet.
Turnkey is also commonly used in motorsports to describe a car being sold with powertrain (engine, transmission, etc.)
[1] The term turnkey is also often used in the technology industry, most commonly to describe pre-built computer "packages" in which everything needed to perform a certain type of task (e.g. audio editing) is put together by the supplier and sold as a bundle.
In commercial use, a building set up to do auto repairs would be defined as turnkey if it came fully stocked with all needed machinery and tools for that particular trade.
This process includes the purchase, construction or rehab (of an existing site), the leasing out to tenants, and then the sale of the property to a buyer.