LARAVEL -> Why try catch not work in Laravel?

I have code in RouteServiceProvider:

$router->bind('user', function ($value) {
    try{
        throw (new \Symfony\Component\HttpKernel\Exception\NotFoundHttpException);
    }catch(Exception $e){
        exit('nott');
    }
});

and I don not geting output

nott

I am getting

Sorry, the page you are looking for could not be found.
NotFoundHttpException in RouteServiceProvider.php line 75:
...

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