Duty Free? 'Cheap-Free' more like

What is the point of duty free shopping when you can find things cheaper on Amazon in your own country? Unless you are a smoker or drinker there really is no point. I'd have thought with the coming of smart phones and the ability to check prices online that they would have changed (here in Seoul Incheon airport they provide excellent wireless for free). But no. I've just come across some cameras, one for 100 dollars more than online and another, 'on special offer!', reduced to the same as Amazon. And that's Amazon in my own country, free delivery and a valid warranty.

Even cosmetics are not the excellent value they seem. This Davidoff aftershave i snapped on the way out was available from Boots Online for £17.