[fjtorres]

Out of curiosity, does anybody know how the different dialog marking schemes evolved?

The US uniformly uses double quotes (regardless of language), I've seen single quotes on british etexts, and Spain and latinamerica favor em-dashes. Wouldn't be surprised to see alternate conventions in other regions.

And, yes, it can be jarring to run into books marked with a different convention than you're used to. I find it so, too. Doesn't stop me from reading them but it does slow me down a bit.

I supposed the differences will probably will be used by publishers as yet another excuse for georestrictions and protectionism, I suppose.