In the platonic ideal for free markets, perfect information is a prerequisite.

In our every day markets on the other hands, companies often fight to conceal information because that allows them better pricing options, but that in fact does make the market less efficient.

Some countries, like Germany, have much stricter laws when in comes to product labeling, they require much more information.

And in some countries, like South Korea, there seems to be natural market demand for a lot more product information.

I think that makes those markets more efficient.