That's because they're doing it wrong: for a tasty iced coffee, don't use stale cold coffee, make a fresh (double) espresso (or any other strong coffee, I suppose) and immediately chill it with ice.
All three produce varying acidity levels of the same horrible drink, IMO. Most people I see drinking iced coffee either A. drown it in sweeteners and cream, or B. just slam it down black for the fastest caffeine intake on a hot day.
I'm sure many people disagree with me, but I've tried it in probably every form there is, and it's just a waste of coffee to me.
[1] http://www.npr.org/sections/thesalt/2012/07/11/156378713/coo...
1. A great cold brew has so much more flavor to me than hot brewed coffee. It also is significantly less acidic, which helps my stomach a lot.
2. If I ever consider the weather while ordering beverages, I do so strictly to avoid an uncomfortable carrying situation (carrying a cold drink in an even colder environment). My warm bloodedness gives me a lot of agency to drink what I want and not what the weather tells me.