Using a policy's this->authorize() check in a laravel controller inside a store() method

So I was reading about using laravel policies for granting authorities on the resources of my application but there seems to be a problem there though I followed the tutorial.

I have a user model which can't be created via HTTP requests except by other users who have the Entrust role of 'Admin' or 'Broker'. What I understood and succeeded to make it work on other actions like indexing users was the following:

Inside the AuthServiceProvider.php inside the private $policies array, I registered that User class with the UserPolicy class like that

class AuthServiceProvider extends ServiceProvider {

    protected $policies = [
        'App\Model' => 'App\Policies\ModelPolicy',
        User::class => UserPolicy::class,
        Insured::class => InsuredPolicy::class
    ];

    public function boot(GateContract $gate)
    {
        $this->registerPolicies($gate);
    }
}

Define the UserPolicy controller class:

class UserPolicy {

    use HandlesAuthorization;

    protected $user;

    public function __construct(User $user) {
        $this->user = $user;
    }

    public function index(User $user) {
        $is_authorized = $user->hasRole('Admin');
        return $is_authorized;
    }

    public function show(User $user, User $user_res) {

        $is_authorized = ($user->id == $user_res->id);
        return $is_authorized;    
    }

    public function store() {
        $is_authorized = $user->hasRole('Admin');
        return $is_authorized;
    }
}

Then inside the UserController class, before performing the critical action I use this->authorize() check to halt or proceed depending on the privilege of the user

class UserController extends Controller
{

    public function index()
    {
        //temporary authentication here
        $users = User::all();
        $this->authorize('index', User::class);
        return $users;
    }

    public function show($id)
    {
        $user = User::find($id);
        $this->authorize('show', $user);
        return $user;
    }

    public function store(Request $request) {


        $user = new User;
        $user->name = $request->get('name');
        $user->email = $request->get('email');
        $user->password = \Hash::make($request->get('password'));

        $this->authorize('store', User::class);

        $user->save();

        return $user;

    }
}

The problem is that $this->authorize() always halts the process on the store action returning exception: This action is unauthorized.

I tried multiple variations for arguments of the authorize() and can't get it to work like the index action

In store() function of UserPolicy::class you are not passing the User model object:

public function store(User $user) {
   $is_authorized = $user->hasRole('Admin');
   return true;
}

missing argument User $user.

Maybe this is the cause of the problem.