Yeah, it's a way to flatter the rest of your customer base, who now get to feel superior for using a different browser. "Hey everybody, I use Chrome, aren't I wonderful?"
Further suggestions to let us elite middle-class types feel superior to others:
1. Extra 25% surcharge for anyone who shows up at your cafe wearing Crocs
2. Anyone driving up to your hotel in a Pontiac Aztek has to pay a fifty-dollar uglification fee
3. If a fat person shows up at your store, employ a security guard to stand around going "Ha ha! Fatty fat fat fat" until they leave.
It would be reasonable to charge extra for anyone who enters a shop with a beautiful wooden floor wearing spikes on their shoes. Spikes induce extra maintenance costs - so does IE7.
So then the IT department chose for them not to be able to use a certain online shop. If the online shopping is work-related, then it's the IT department's job to facilitate this and upgrade the systems. If the online shopping is not work-related, you have the option to do it in your own time, with your own browser on your own PC--the same situation as people that do not spend their working hours surfing the web (because they might not have office jobs).
Not illegal in Australia, where kogan is from. Unfortunately there's no limit on the amount a merchant can charge for payment/card fees. For example, I believe the most popular taxi charge company here (CabCharge) charges a 10% fee when paying by credit card.
But places can just offer s "cash discount" and it ends up being exactly the same. All the gas stations around me charge 10 cents more for credit cards and it's infuriating.
I guess the major economic difference is all those suggestions would lose you money, whereas this will probably help their sales while slightly cutting their costs.
Here's a baseless graph that John Resig of jQuery fame included years ago in a speaking session: http://i.imgur.com/1OOcg.png.
Developers are inundated with "ugh; IE sux" propaganda, but the complaints are rarely quantified beyond "my site breaks in IE".