@OntheRoses no, position of baby and cord are not determinant in birth modes. About 1/4 to 1/3 of all babies have the cord around the neck and have no difficulties being born vaginally. The cord is elastic and it is quite common that, during pregnancy, it gets tangled around different parts of the body, so it is prepared for that and grows and stretches accordingly. In 5 years as a midwife, I have delivered hundreds of babies with the cord around the neck, and still have not needed to cut a cord before the baby is delivered. Very occassionally, the cord is too short (and this happens whether or not it is around the neck) and can pull on the placenta during the pushing phase. This is what is risky and results in deep decelerations which inform us that the baby is running out of oxygen. Whether the cord "strangles" the baby is not that determinant, as the baby does not need to breath until they are out. It is the pulling of the cord on the placenta, and the interruption of the blood flow to the baby, that means intervention to get that baby out is crucial. This would not be seen on US scan, as the length pof the cord is impossible to determine.
You are right that babies whose position is persistent posterior often cause longer, more painful labours. However, persistent posterior all the way through labour happens in a minority of labours. Most babies turn to anterior before birth (sometimes right before pushing). There are factors that make a baby more likely to remain posterior, such as having an epidural (as the mother loses the ability to mobilise and help baby turn). In your case, having had an epidural likely contributed to your baby being posterior all the way through labour and pushing. An epidural in itself already increases the chance of needing an instrumental birth, but if the epidural happens when the baby is posterior, the chances of emergency CS also increase significantly. When a baby is posterior, it is even more important for the mother to be mobile.
No obstetrician or midwife would offer a CS for a baby with the cord around the neck or posterior on US scan, so doing a debside scan on every labouring woman just because of this would be a waste of resources.
In the gentlest way possible, your experience has tainted your judgement of birth. You have gone through a huge amount of trauma, due both to lack of skill of your midwife and a number of circumstances which were out of anyone's control. Your brain is trying to make sense of what happened. That is probably why you're arguing so passionately in a thread that has nothing to do with what you're arguing about. This thread is about the advantages of VB vs. elective cesarean section, and your experience, while very traumatic, has nothing to do with this debate. You have said very clearly that you don't trust midwives, so I believe you will oppose anything a midwife says here, which is your issue, not mine. Unlike many other midwives, I have a background in research, molecular biology and genetics, and if there is something I can argue, is past and current evidence.
Which is not the same as arguing what is better for any specific woman and her birth. For a specific woman, in my opinion, the best way to have her baby is the way she decides once she has been given unbiased information and allowed to contrast it herself and clump it together with her own experience and background.