Wirelessly posted (Opera/9.80 (J2ME/MIDP; Opera Mini/4.2.13337/1006; U; en) Presto/2.2.0)

Out of my last 4 flights to and from Bangkok on TG I've had the pleasure of being bussed to the terminal.
This in spite of the umpteen gates that had no planes sitting in front of them.
On two of these flights, (leaving and arriving in the wee hours of the morning) the captain decided to park the plane at the very furthest corner of the airport "parking area", even though there were wide open spaces available for the taking.
How does the use of gates and parking slots get decided anyhow? Given that TG's on its home hub, I would expect them to get some priority...