This is, of course, the obvious counter-argument, but even in cases of complication it's usually not a problem getting EMS there in time. In parts of the US, midwifery is illegal, but there are places like this (
http://www.ncbirthcenter.com/) that provide midwife services in a natural, homelike setting, but which also have hospital privileges and an OB/GYN on staff in case anything goes wrong. There's another important bit, too. Doulas (
http://www.dona.org/mothers/) are becoming much more popular, in an effort to provide a similar kind of support through labor & delivery as a midwife might, but within a hospital setting. We used one with our two children and it was really calming to have someone around who wasn't hospital staff AND had experienced hundreds of births AND was there to do whatever my wife needed throughout.
My mother-in-law is a retired nurse midwife who delivered >600 babies in England & Scotland during her career before moving to the US. I don't know if it's still true, but she tells us that in the UK, midwives have special privileges for things like transportation -- free bus/train/subway, and the ability to hail a cab and get a free ride if it's necessary. This may not be true any longer. She relocated in 1969.