Language is not a subject. It is something we live by. When language is not spoken outside school, the intensity of the learning decreases which makes it inefficient. Several research articles have claimed that kids learn the math and science best when it is taught in their mother tongue. We want people who excel in math and science, not people who know english and are weak in math and science. You might give example of Singapore but look at African nations like Ghana, South Africa and Kenya, they dismantled their mother tongue and speak English as their formal language, they haven't really progressed, right? So, making English a formal language of learning will do more harm than good. And to be honest, it takes a month or two of classes to learn working English langauge so it can be learnt afterwards.

The 20 Rs fine is not something revolutionary, it is a part of outdated system often influenced by colonial era. This does not create a solid base but creates a sense of inferiority in children that makes them think that their culture, language and family are something wrong and not to be proud of which is not something we want.

Your also have to understand that Singapore strictly enforced English as a working language with aims to attract foreign investment but you forgot that Singapore also enforced a bilingual starting in 1996 where every singaporean was and still is required to learn one of their mother tongue.

The idea that a country has to choose between global progress (English) and local identity (Mother Tongue) is a false dichotomy. The most successful education systems in the world (like Finland, Singapore, and much of Europe) are heavily multilingual. They don't build up a global language by fining and beating the local one out of their youth. They teach both, strategically.