Then they must have flush handles rebated into the sides of the doors so you can open them. You can have a pull handle rebated into the front edge of the door which means that the door can slide back to being flush with the frame but they are a pain to use.
They have installed it correctly ( if that's what you wanted that is ) and commonly buy a frame for a 720 door to allow for an 820 door to sit out 75-100mm proud.
Stewie