PPP makes no sense when it comes to comparing data usage between countries. Data is not based on same supply/demand characteristics as physical goods. It is quite literally arbitrary. Much like most software you buy/subscribe to. Ever bought a digital product at 90% discount during Black Friday or Cyber Monday? Why don't you find physical products with 90% discounts (unless it is a clearance sale)? Because you can't discount cost involved in acquiring raw materials and labour cost. Digital products on the other hand can be duplicated infinite times with zero additional cost. So is anything connected to it (which includes data, storage and processing). Sure there is some cost involved. But at scale that cost becomes negligible. You can't produce physical products at scale without the cost also scaling proportionally.
Even in India, before Jio made its entry, data was extremely expensive. Horrible speeds, very low data limits and no competitive pricing (you can say that it was a data cartel of sorts). Jio disrupted the entire sector. All ISPs reduced prices overnight. How could they do it? Wouldn't it hit their bottom line? Nope! They never went into loss in the first place. They charged exorbitant rates because they could. Not because there was some basis for it. That monopoly was disrupted. That is all there is to it.
And with a billion+ people in the country, ISPs will never go under loss for selling data for few cents - a dollar. Rather, they are probably making more than they ever did. Jio showed them the way to price correctly.