Laravel controller based api routing - laravel-routing

Question

My normal web app runs w/o any issue. Then I wanted to experiment with APIs. I enabled Passport since I need api authorization (but at this moment, I rather want to get this thing working and I have no idea whether it is a problem with Passport) and I wanted to get simple json output of specific Product. So far, I was not able to get it working. I'll describe contents of each file and if someone can direct me to find the issue in my code, that would be great.
Resources\Product.php
namespace App\Http\Resources;
use Illuminate\Http\Resources\Json\JsonResource;
class Product extends JsonResource
{
public function toArray($request)
{
return parent::toArray($request);
}
}
Providers\AuthServiceProviders.php
public function boot()
{
$this->registerPolicies();
Passport::routes();
}
User.php
class User extends Authenticatable
{
use HasApiTokens, Notifiable;
...
}
ProductController.php
class ProductController extends Controller
{
public function __construct()
{
$this->middleware('auth');
}
public function apiShow(Product $product)
{
return new ProductResource($product);
}
...
}
routes/api.php
Route::get('/products/{product}', 'ProductController#apiShow');
Now if I go to http://localhost/public/products/1, it displays the page as expected. But if I type in http://localhost/public/api/products/1, it will always go to home page which is set to localhost/public in HomeController.
If I modify routes/api.php as:
Route::get('/products/{id}', function($id) {
return Product::find($id);
});
I get the correct json output in the browser.