Zone 1 and 3 used to have (still do it seems) lanes for F/J pax - was really just a tape lane with a checker looking at BPs. There was also a grand entrance between them with ‘Fast Track’ and ‘Thailand Elite’ and other branding (I think).

Perhaps too many F/J lax were drawn to this branded entrance and congestion was increasing. Of course, the signage for the tape lanes is/was almost non-existent, so pax can be forgiven to being drawn to this particular entry.