Research reveals negative effects of academic preschools and kindergartens. From the Psychology Today article:
The results are quite consistent from study to study: Early academic training somewhat increases children’s immediate scores on the specific tests that the training is aimed at (no surprise), but these initial gains wash out within 1 to 3 years and, at least in some studies, are eventually reversed. Perhaps more tragic than the lack of long-term academic advantage of early academic instruction is evidence that such instruction can produce long-term harm, especially in the realms of social and emotional development.
So, of course our government is trying to institute universal educational pre-school for all.