I don't think this is a contradiction, just a higher standard for stairs which need to meet requirements for stairs which are considered part of the accessible means of egress.  The reason for the 48 inch requirement between handrails here is because people with mobility issues may require assistance down or up the stairs.  This 48 inches theoretically provides enough room for two or three people to carry a person with mobility issues down to the level of exit discharge.  Whereas exit access stair requirements are based on self rescue.

Ref. 2015 IBC Code and Commentary.  ( I am listing this here, because the current system only allows you to select from a list of previously entered references.  :-\ )