In Magento, you can choose by country if you want this field or not. So I guess it’s true for most of the online shop solutions.

But as stated by others (about Ireland in their example), even companies that had their hq there asked for zip code at a time there was not any.

So I guess if you start shipping internationally, it’s a big job to make a form that fits every cases.

I wonder if someone have made a list of those particularities. Could be a good idea if not.