Door cill height

[somebodyyouknow]

I’ve just had a new composite door installed and am concerned it has not been measured correctly. The door has been sat on something like a 2x4 and that just covered in edging trim and let’s a draft in. It seems to be way too high with the door about 4 1/2 - 5 inches off the floor inside. The cill is really high outside as pictured and you can see the wood as below. Is this normal or is there a genuine reason for this?

 

[crank39]

What does it look like inside