Whilst Bookworm mentioned the lower certification criteria the actual value will be the lower of two values - either the highest windspeed at which controllability was not an issue (TPs assume the 'net pilot') or the highest value witnessed (often seeked out) during the certification period.
I don't think it even has to be that:
23.233 Directional stability and control
(a) A 90 degree cross-component of wind velocity, demonstrated to be safe for taxiing, takeoff, and landing must be established and must be not less than 0.2 Vso.
23.1585 Operating procedures.
(a) For all airplanes, information concerning normal, abnormal (if applicable), and emergency procedures and other pertinent information necessary for safe operation and the achievement of the scheduled performance must be furnished, including--
...
(2) The maximum demonstrated values of crosswind for takeoff and landing, and procedures and information pertinent to operations in crosswinds;
The value recorded for the purposes of 23.1585 is the maximum value that was
demonstrated for the purposes of 23.233. There is no requirement that this is the highest value
witnessed.