如果它在laravel别名中，为什么还需要使用该类？

Why do you still need to say:

use MyClass\Table\Facades\Table;

at the top of a laravel controller

even if you have specified it in app/config/app.php

'aliases' => [
    'Table'     => MyClass\Table\Facades\Table::class,

You don't?

'aliases' => [
    'MyClass' => Some\Vendor\Something\Facades\MyClass::class,
]

Then you can do

use Myclass;

class MyController extends Controller {
    public function fetch($id) {
        return MyClass::find(1)
}