They can be unlocked mid contract, but with a cost. https://www.cable.co.uk/guides/how-to-unlock-your-mobile-phone/
Some vendors actually do it for free mid contract if you ask nicely.
My MacBook Air is from 2011 and very fast on Mavericks. My iMac is from 2010 and with an upgrade to 16GB RAM it positively flies - oh and the small matter of a £600 resale value makes it more than worthwhile, considering I bought it for £1200 3 years ago.
Thanks to Vodafone excellent 12month contract deal, I will be selling on my 5s and getting the smaller 4.7" 6 when it comes out. Anyone interested in a mint 5s?
Put the news s tory in context - "Apple is not the only electronics company doing business within a troubling supply system. Bleak working conditions have been documented at factories manufacturing products for Dell, Hewlett-Packard, I.B.M., Lenovo, Motorola, Nokia, Sony, Toshiba and others. "