Alliance and Horde Read Together

I was ravishing Southshore the other day when I came across an in-game book. I
am sure you have seen many of these lying around throughout your travels, but what about in an opposing faction's town? I never thought that I would be able to even open it.

As it turns out, you can read them. Not only that, but you can understand them as well. I would have assumed that since Horde and Alliance can not speak to each other, than surely they would not be able read the same language. Do you think there is a reason why this is possible? Maybe our languages are somehow derived from an Adamic Language. Or simply an overlooked detail that Blizzard never took into account. I bet it's a conspiracy. Blizzard is hiding something from all of us. George Bush, Bill Clinton, Donald Trump, Martin Sheen, they're all in it together.

Trust no one!