Grosjean argues that there has been a monolingual bias regarding who is considered a 'bilingual' in which people who do not have equal competence in all their languages are judged as not speaking properly. 'Balanced bilinguals' are, in fact, very rare.
Grosjean argues that the notion of 'bilingualism' is biased towards monolingual standards, where individuals with unequal proficiency across their languages are judged as not speaking properly. The existence of "balanced bilinguals" is exceptionally uncommon.