This trade-in is available in only a few countries - the US, France, the UK, Germany, Canada, and Italy - but not India. If you go by the technicalities of the trade-in programme, it's true that India is once again missing from this list of countries. But in a practical sense, it isn't.
Here's how. Apple first introduced its iPhone trade-in programme in the US market in September 2013. It allowed an existing iPhone user to exchange an old iPhone model for a new iPhone at a slightly discounted price. But much before the introduction of this programme, Apple had introduced a 'Buy Back' scheme in India. In April 2013, the company started advertising the 'Buy Back' offers in leading newspapers, allowing consumers to get up to Rs 7,000 off for an old smartphone on the purchase of the iPhone 4.
Sure, there is a big difference. In the US, one gets the offer for the latest launched iPhone models, but in India, the Buy Back schemes have been for older generation smartphones such as iPhone 4, iPhone 5 and iPhone 5c.
However, the 'Buy Back' program in India, from day one, offered the convenience of exchanging not just an iPhone but other brands too. For instance, in April 2013, people got maximum of up to Rs 7,000 off for their old BlackBerry 8520. The resale value of the BlackBerry 8520 at that time was close to Rs 2,500 only. Initially, Apple accepted only a few select brands such as BlackBerry, Nokia, Samsung and Sony. But later it started to accept models from brands such as Micromax, Lava and Karbonn, too.
Honestly, in my opinion, what Apple is implementing just now, had been in India for a long time. The method might be different but the principle remains the same.