why change value in Eloquent ORM?

I face small puzzle problem in Laravel select query. It automatic change data type.

When i use

$data = Model::select('user_id AS id')->get(); 
data is [{"id":3},{"id":4}] // not actual value

But When i use (only change Alice id to ID)

$data = Model::select('user_id AS ID')->get(); 
data is [{"ID":"03"},{"ID":"04"}] // actual value

what is the problem

via Chebli Mohamed