Ah I had never read an article about it, just saw the phone plans and talked to folks when I was there. Minimum googling brought me here - https://www.google.com/amp/s/qz.com/333313/milliions-of-face...

I'm not from SE Asia, but from Romania. This kind of thing happens everywhere:

https://www.vodafone.ro/shop/abonamente-de-date#tab-1

-> "Detalii abonament"

-> Social Pass: [...] (Facebook, Facebook Messenger, Instagram, Whatsapp, Pinterest, Twitter, Viber)

It's widespread around the world, except for the US, until recently.

Also available in SA. You have to share your facebook data with the mobile company though.