Why is it possible to omit default values in overridden member functions of sub-types?

Question

Just as stated in the title: Why is it possible to omit default values in overridden member functions of sub-types?

Is this normal or to be expected?

Answer 1

Yes, this is normal and to be expected.

Moreover, it is not allowed to override the default values. This does not compile:

interface Foo {
    fun bar(parameter: Int = 1)
}

class Baz : Foo {
    override fun bar(parameter: Int = 1) { // ERROR: An overriding function is not allowed to specify default values for its parameters
    }
}

Technically the implementation with fixed default values is much simpler than any other implementation. For example Scala goes to a great extend to provide this capability, but the generated byte code is not a simple one.