`packages` keys do not appear to be true paths

Documentation for the keys of the packages property in package-lock.json files describes them as "relative paths from the root project folder". This does not appear to be entirely true.

Consider the following package.json:

package.json:

{
  "name": "my-project",
  "dependencies": {
    "@scope/package-a": "^1.0.0",
  }
}

Assume also that "@scope/package-a" has a dependency on a package called "@scope.package-b". When npm installs dependencies, the project directory structure looks like this:

my-project
├─node_modules
│ └─@scope
│   ├─package-a
│   └─package-b
├─package.json
└─package-lock.json

However, package-lock.json has the following entry under packages:

"node_modules/@scope/package-a/node_modules/@scope/package-b": {
  "version": "1.0.0",
  ...
},

Notice the path does not actually exist in the directory.

Documentation should be clear about whether this is expected or whether the relative paths, as described, are true paths.

Start by locating the documentation for the packages property in package-lock.json and reproduce the shown scoped-dependency layout with npm. Done when the docs explicitly explain whether package keys are logical dependency locations rather than filesystem paths, including the nested scoped-package example.