I once tried to read the Terms & Conditions of I think it was the the Rabbit Card for travel on the BTS. They were very extensive, and stated that customers agreed to being videotaped on BTS stations, recorded on microphones and tracked throughout the system.
Seeing as nowadays, under the excuse of preventing money laundering, users are required to give ID or Passport details to obtain the Rabbit Card, it's easy to track and identify anyone and everyone as they pass through the ticket barriers.
It's not hard to imagine that the BTS are doing exactly the same.
I tried posting them here on AN once on a thread about privacy, but they were removed for some reason by a moderator.