Well from the book Val it seems like the USA and china both do not use the zeros, but only the Chinese teachers understood that you COULD use zeros, how, why, etc but would still encourage moving back to blanks. The problem discussed is how to help a child who is right aligning every line of the problem (no blanks OR zeros). Most of the American teachers had a purely procedural knowledge and could do more than tell the kids "do it this way because it works" some thought adding zeros was actively wrong....

I'd be interest in how a whole list of countries deal with this too...