I don’t see how they’re going to save any money. It appears to me that assembling wheelbarrows and barbecue grills is a collateral duty. They have a few floor models (wheelbarrows are usually outside). If you want them to assemble it, they charge you extra, but it’s an employee who otherwise works the floor who assembles it for you.
Is any Lowe’s selling so many wheelbarrows and barbecue grills that assembling them is a full time job?
Any single Lowes? Probably not.
That means it's probably more efficient to have a crew which handles the assembly for all the Lowes stores in an area, visiting each store in turn.