I think that it is both resources and size of the movements and focus. The USSR and CPC didn't seem to really prioritize converting everyone to that extent and there is no other Marxist movement with the resources to do much of this. Many Marxist organizations will prioritize other actions and struggles rather than pure accessibility and evangelism. Where both there are large Christian organizations and donations from rich Christians to fund this work.

I did end up being dragged to a Protestant church for Easter Sunday, and I did meet a guy doing this type of work. He is a linguist and is supported for 6-9 months a year to go to a Western African nation and work on developing written scripts for several of the indigenous languages that don't have one, as the first step to translating the Bible to that language. So that they don't have to learn English or French to read the Bible. And that is just one missionary organization working in a small nation that already has a not insignificant Christian population due to colonialism.