That stat is misleading when you compare percentages against raw figures:
1 million: Free Basics users in India in 2015 (source: FB press release)
5.8 million: Data users acquired by Reliance, FB's sole partner in India, in 2015 (source: IAMAI)
109 million: Data users acquired by all telcos in India in 2015 (Sep 2014-Sep 2015, source: same IAMAI report)
So if Free Basics converted 50% of their users to the full Internet, that's about 500k users, or less than 0.5% of the industry's success rate.
Asking for dangerous policy exceptions because your flawed scheme has an actual success rate of 0.5% and presenting this as 50% is disingenuous at best.