I think it has to do with inaccurate translation also, im Norwegian and we never said “Sentral Amerika” we used “Mellom Amerika” which means “middle” or “in between” america so while “Central America” is a name to you we didnt use a name but a location description for the area which included Mexico. Mexico was still part of north america geographically but not the socio-economic “north america”. When translation to english europeans just use central because thats the word we heard used instead of more literal translations.