"The formal EPSG definition provides the axis-order used to interpret coordinate values." -> https://docs.geoserver.org/latest/en/user/services/wfs/axis_order.html
Script result:
From 6556 EPSG codes evaluated, 61.2% defines Long/Lat order and 38.8% defines Lat/Long order.
GeoJson is right about 61.2% of the time.
P.S. That was fun.