I don’t know if there anything wrong with the mass transportation system in Thailand when we introduced the system to people. Or at that time it’s not necessary to start with using it right. Or we’re problematic to be systematic. I heard about a campaign that try to improve bus etiquette years ago like board at the front door, walk to the rear find a seat, and use the rear door when exiting. The situation looked good when we just had Euro bus (not sure with the name but it’s the new model, the yellowish orange one, the most pricey ticket one.) Shortly after, we backed to where we were. And, now thing that was designed to disallow people to get on the bus at the rear door is opened all the time.
I’m preparing for my traveling to French Riviera. What I do is to study the system there, to do it right, not to lose my face, to get prepared, to avoid any problem that could happen in the trip because I know they don’t speak English (they understand but just they use French with you.)
Hence, I learn how to use the system since the beginning, make a sign to the bus driver if it seems no one else taking the bus (O.K. this is not a rule but this is what French do), board on the bus at the front door, validate the ticket on the bus (the machine is close to the front door), press on the red button "Arrêt demandé" (stop requested), exit from the rear or central door.
Now, I’m thinking what instructions can be when foreigners wanna take a bus in Bangkok. Perhaps, it’s much easier for me to tell them: get on the bus; find a seat; pay for a ticket, a clerk just walks around tell him/her your destination; get off when arriving the destination. More convenient (get on/off at any doors), easier (fewer steps to remember), and just skip for any shortcoming. However, these things get better with BTS (skytrains) and MTRL (subways).
Oh, I just have a second thought, maybe we’re smart, in BKK buses are always crowded esp. during rush hours, so we need to relax rules, adjust the system to serve us best – to get on and off at any doors is not too bad in such situation.
By the way, hand signaling for one is up your thumb, for two is a V-sign, up your thumb and index.