I know this happens but I have personally never seen this happen although heard stories from colleagues. I am a recently qualified midwife. However, I have had an anesthetist refuse me once to do one when I was student, I ended up calling the consultant on call but the woman delivered her baby in the meantime so was too late. I was horrified and made a complaint.
I have seen women who request them not get them but this has been due to the anesthetist not being available due to a queue of women waiting or emergency in theatre. Then baby is born before their turn. Unfortunately in these cases the midwife gets the blame as they are the one in the room. Only time I have ever felt threatened was due to an instance like this.
In my experience we actually encourage them before syntocinon is commenced.
I try and have honest and open discussions early on (if possible) about pain relief in labour with risks and benefits and let the woman know she can change her mind at any point (unless she is pushing or unable to stay still enough for it to be sited). Pain relief is there for a reason, you aren't a better mother because you opt for it. 100% the woman's choice. We have it for all other painful procedures so why are we so against it for childbirth? I myself was anti epidural when I had my own child. No idea why!
When I had my son it was actually the opposite. They were pushing me to have an epidural that I didn't want as I said I needed to push and refused me gas and air as 'no way you are more than 3cm, 1st baby it's too quick, it's just the drip and position of baby making you feel you need to push' and they refused to examine me due to infection risks.
In the end I agreed to the epidural but unable to stay still, involuntary pushing and it was the amazing anesthetist who was trying to site it made the midwife examine me as I kept begging and she refused. Funnily enough I was fully dilated and his head was right there so he gave me the gas and air and wished me well and he was born 16 minutes later (unfortunately I ended up in theatre for my placenta to be removed so met him again for my spinal and he was so lovely and apologetic).
Horrible to hear these stories and I am so sorry to all those women with these bad experiences. Part of the reason I wanted to become a midwife was due to my own poor experience, I wanted to make any difference I could.