Why can't an interface implementation return a more specific type?

Question

If an interface specifies a property or method to return another interface, why is it not allowed for implementations of the first interface to \"change\" the return type in

Answer 1

It was not implemented, because they didn't feel like the feature would justify the effort. But there are good news.

This feature has been announced in a post by Mads Torgersen in March 2020, for the upcomming C# 9.0

abstract class Animal
{
    public abstract Food GetFood();
    ...
}
class Tiger : Animal
{
    public override Meat GetFood() => ...;
}