Women labour very differently.
The problem before you're in active labour (less than 4 cm dilated) is that, if they give you an epidural, labour is likely to stall and then they interventions (and hence risk for you and baby) start rolling.
Also, an epidural means one-on-one care, and an early one will mean the ward has one less midwife for many, many hours on end, so there's the staff isue too.
And there is not much more than an epidural you can get while you're still pregnant, as anything in your blood will get to baby too. We use morphine IM, which tends to work very well for about 3 hours. But for some women it just doesn't, or for longer latent phases you can't just keep pumping morphine in without risks.
Midwives and doctors are not on a competition to make women suffer. unfortunatelky this is how women's bodies give birth. Until very recently in history there was zero pain relief,. and this is what women went through.
Some may say "just get a cesarean", however unneccessary cesarean sections have already increased risks in future pregnancies (placenta accreta and percreta, postpartum hemorrhage, wound infections, hysterectomies, endometritis, uterine rupture and higher risk of miscarriage and stillbirth for future babies regardless how they're born). To give you a specific example, placenta accreta (which often results in haemorrhage and hysterectomy) has increased 4 times since the 19802 as a result of having so many cesareans.