I suspect that there are not any good studies that will give you a comprehensive answer. You might be able to find a compilation of official national educational policies that covers a sufficient number of countries, but official policy and reality are different things. For example, policy used to be in Tanzania and AFAIK still in Kenya that for one or two years there would be "mother tongue education", but policy was doesn't reflect reality when there exist no mother tongue resources (for which reason Kenya and Tanzania differed in the extent to which they could provide mother tongue education, and this also accounts substantially for the actual high degree of mother tongue instruction in South Africa, whose law is here). This study speaks of the benefits of "local language" instruction, but the case study involves primary schools in Zanzibar where the national language, Swahili, is actually the local language.
Indeed, actual "mother tongue" education is rarely even a policy reality, instead you find "local language" education (which differ when people move around). National-level surveys of language policy and attitudes at least in Africa are few, far-between, and not particularly reliable. I would hesitate to extrapolate from European language practices to the rest of the world.