One impression I have always gotten from the series is that Earth medical technology is very advanced compared to the rest of the younger races. When the Centauri Emporer was dying, they left him in the care of B5, even though his personal cruiser (which undoubtedly had a full medical suite aboard) was just a five minute shuttle ride away. Later, when Delenn is stabbed by the Nightwatch, she is treated in Medlab while three Minbari cruisers orbit the station. If these other races thought they had superior medical facilities, wouldn't they have insisted on using them? Later, Franklin and and an th medical facility are chosen to do the studies on interspecies cross contamination risks for the entire Interstellar Alliance.
Earth may be backwards in many ways, but medicine does not appear to be one of them.