Ok, so Thai Airways & Thai Smile Air are the only ones that have this terrible policy. If you want to book a flight for someone else, you must go to the Thai Airways office (in Bangkok, it's in Vibhavadi out near Don Muang airport). You have to sign a confirmation form, and let them scan your credit/debit card and your passport. WTF is this bullshit????? (Their consent form regulations page is here)
Air Asia, Nok Air, Thai Lion Air etc all don't have this. Thai Airways is so old school , their website, their policies, you cant even choose your seats online (have to choose at checkin desk), their "i checkin" and "manage booking" on their website is always broken. If you are using VPN you cannot book flights.
I flew on Thai Smile Air today, bought a couple beers at the Khon Kaen airport to drink on the airplane, and they even came and took my beer away saying that absolutely no alcohol is allowed to be drank on their flights
WTF WTF WTF