They could also just tell you "the items you want to buy cost $X for shipping" where X just happens to drop to 0 under certain circumstances. This is what everyone except Amazon does. Charging for shipping is entirely understandable. I too love free shipping, but it's actually us that have been spoiled by Amazon.

And with Amazon's low prices and 5% cashback I'm pretty sure even if they started charging for shipping that it would be still cheaper than anywhere else ...