The distribution of zero form copula or copula omission in New Englishes, AAVE and some English creoles induces two hypotheses. One is imperfect learning hypothesis based on second language learners' simplification and generalization. The other is the possibility that the pattern reflects a shared substrate influence from local/first languages or other historical contact factors. Our study aims to suggest a more basic principle behind these factors, arguing that from the perspective of the syntactic constructions that express the linking between the subject and the predicate, the most economic way of the expression is the phonologically null form. We suggest that the advent of the zero form copula in New Englishes and AAVE is best explained by imperfect second language learning hypothesis. We also argue that the hypothesis can be comprised in the broad sense of economy principle in view of general language evolution.