The White Coats are a culture of physicians, who wander the countryside to dispense medical treatment where ever they can. In many ways, they are like the Bookkeepers, but are better organized. They often work with the Bookkeepers, to acquire medical books and journals, and the Freemen Alliance to build hospitals and to repair local infrastructure - which in turn, improves the health and hygiene of the people. They are guided by the Hippocratic Oath to "do no harm," to "avoid being judgmental" and to "never exploit those in need." As medical experts are it high demand, they are universally welcomed, and are given a degree of hospitality seldom seen in the Post-Armageddon Wars.
There are few people who would reject their services - usually out of pride of health, or religious dogma - or to harm them. Those who would harm them are ether savage desperadoes, or members of S.C.U.M. The leadership of S.C.U.M. sees medical treatment as a weakness, and soldiers who have been treated are stigmatized for it. On the other hand, they have no issue with substance abuse - be it recreational or performance enhancement - or biological warfare, and are not above torturing them to get there way. For most people, there is to greater sin then to harm or kill a White Coat. Groups and communities that are known for killing White Coats are avoided by White Coats.
When they travel, they would do so by joining a caravan, or ride in a personal vehicle, if available. Nomads not just enjoy any medical aid, but a White Coat is like a magic ticket in even the most xenophobic community. Once in a community, locals would typically bombard the physician with pleas for medical treat or advice. The physician would be provided with free food and the best lodgings available. One of the big risks faced by a White Coat is that they can get spoiled by the hospitality. This is generally frowned upon by the White Coat culture, as they lose objectivity, and risks ruining the good reputation of their profession. Another risk faced by the White Coat culture, are impersonators. There is no shortage of people who covet the glory, hospitality and adulation given to a White Coat and it is not unusual for con-artists to impersonate White Coats for the sake of the benefits. These "Bleach Coats" are despised as much as anyone would inflict harm on a White Coat, as they are usually not skilled enough to treat people with serious injuries or aliments, and are not trusted with anything told in confidence. If caught, they are dealt with harshly. The White Coat culture is a little more sympathetic, but they know the danger "Bleach Coats" have on their upstanding reputation.
White Coats, who are no longer fit to travel, becomes full-time teachers at one of the few operating medical universes. These universes are typically an abandoned hospital, with working utilities. The White Coats have a deal with a Company Town that still produces vehicles, and another that produces medical supplies. The agreement is that they produce ambulances and medical supplies, and the White Coats provides a full-time medical staff for the towns - with priority to the families who run the companies. The White Coats are not proud of this arrangement, but is seen as necessary for the need of the origination.