Speaking English in an Indian school classroom carries a social risk that most students are acutely aware of. Pronunciation errors invite teasing. Grammatical mistakes invite correction public correction in front of everyone. The student who tries and fails visibly pays a social price. The student who stays silent pays no immediate price at all.
Over time the rational calculus of this situation produces what teachers observe: the silence. Students develop a habit of not speaking English in precisely the environment where they most need to practice it because that environment makes the cost of trying too high relative to the perceived benefit.
Changing this pattern requires changing the environment not just encouraging students to try harder but creating a context in which trying feels genuinely safe.