Players in the Grade A carriages actually had an identity-probing function before as well.
Back when they first boarded the train, Renee Kane had spent 500 Life Value to probe Vincent Sherman's information and location.
But the prerequisite for this function was knowing the target's real name and game ID.
Back then, everyone had just entered the game. Never mind changing their IDs, most hadn't even fully grasped their own situation. This was what allowed Renee Kane to seize the initiative.
For other probes based on items or skills, the main prerequisite was likely also obtaining the target's game ID, and they probably cost at least 1,000 Life Value per use.
And that was a low estimate. After all, on the train, real names were far more important than IDs.
