An x-ray will cost 5 or 6 times as much as a scan, and require at least sedation, whereas scanning only involves the bitch standing on the floor. Also I hope you'd not accept oxytocin being given without having confirmed that labour had started as you could end up with a ruptured uterus.
Again I didn't go for x-ray until the end of the pregnancy, and if my vet needed to know whether the bitch was in fact empty, or not. If that involved sedation, then that's what happened. Actually with a patient who will tolerate this, as mine did, and I was right there, wearing a lead apron, which was more likely to be done in Canada than in the UK, sedation/knocking out wasn't needed. Vets out there tended to be far more hands-on with their clients than has been my experience back in the UK. And for sure, I'm quite aware of the dangers of administering oxytocin. Mine tended to go to secondary inertia - so yes, labour most certainly would have started. In fact one of my Canadian vets gave me a couple of shots to administer myself at home as we lived out of town by some distance but in fact after giving her the first with no result, I wasn't comfortable about giving the second, so took her back. At that point, they went ahead with a C.Section. Again, what's 'right' or not right, depends on what WORKS for each of us, at the time.