They will give sell you an unlocked phone at launch - but not SIM free.

Last year it took two weeks before they sold SIM free one: https://9to5mac.com/2015/10/08/sim-free-unlocked-iphone-6s/.

It took 4 months for the 6 https://www.engadget.com/2015/01/06/apple-sim-free-iphone6/.

It took 2 months for the 5s.

I'm sure it's due to some business BULLSHIT. I have called 1-800-MY-APPLE and complained the last 3 years.

Also, whats weird is that there are several different models of iPhones with different radio bands - it's not un-confusing: http://www.redmondpie.com/the-difference-between-unlocked-t-mobile-and-sim-free-iphone-6-6-plus-explained/