Most pick-a-part type salvage yards only have older model cars. The one I visit typically has only cars that are 10 years or older.
the pick-a-part salvage yards I am familiar with have a sister operation that is the newer cars. These are not pick-a-part, but traditional salvage yards, where they pull the part. Parts from newer cars carry more value. The salvage yards like to make sure parts are removed as an assembly. Once they have got what they can from them, then they move the cars to the pick-a-part lots, where everyone can hack off whatever part they want, typically destroying other items in the process.
I can understand why salvage yards don't turn the newer cars over to this type of treatment. They would loose a lot of potentially profitable parts that way.