Actually most countries in the world do immunize against TB. And developing countries in particular overwhelmingly do. The US doesn't mandate and most European countries have stopped.
An interesting observation about that map is that there is a high correlation between countries that stopped BCG vaccinations and high fatality rate from Covid-19. However, Australia is one of the countries that stopped doing BCG vaccinations but it does not have the high fatality rate of western European countries. What's going on there?
Idk. There's so many confounding factors. I don't know when they stopped the vaccination, but maybe it was recent enough that the vulnerable (elderly) did actually receive the vaccination? Maybe temperature does matter. Maybe they're just behind on the curve. We can only wait and see as more clinical data becomes available.
That said, I agree there is an absence of evidence... It's all speculation at this point.