I suspect it is more about differences in operating culture and training. A high proportion of one operator's flying is into smaller airports with short, narrow runways outside controlled airspace on non-precision approaches, yet the other is very used to big airports with full radar cover and navaids. Each trains well for what they do and their crews are very experienced in it. Start to cross the dividing lines and the result will always be uncertain. Neither operator is operating unsafely, and this decision is evidence of that, but it is very much a case of "horses for courses".