Yesterday, I drove from Chiang Mai to Singburi and saw about 50 lorries with their right door wide open. 

What's that all about? 

Offloading crypto.

Those lorries have the '150' model aircons fitted.     ........ 1 door open and 50 mph! 

Save getting out the cab at road police check points.

22 minutes ago, Kwasaki said:

Save getting out the cab at road police check points.

Good point, but is there any reason it has to be the right hand door?

51 minutes ago, Olmate said:

Those lorries have the '150' model aircons fitted.     ........ 1 door open and 50 mph! 

Does the driver also get discount on the M150 energy drink?

55 minutes ago, Neeranam said:

Good point, but is there any reason it has to be the right hand door?

Er - drivers usually sit on the right hand side of a vehicle in Thailand.

You expect them to get out via the passenger seat?

2 hours ago, Neeranam said:

Good point, but is there any reason it has to be the right hand door?

I wonder if that's the one that closes last...meaning it is the first one that is opened. That is, the vertical lip of the right-hand door sits on top of the left-hand door. So the first door to open and pin back would be the right. ...Just a thought.

So it's easy to see that they are empty.

I'm not sure where exactly it matters, but might be multiple points:

Maybe they don't have to weigh at weighing stations if they are empty

Maybe police won't ask them to open their trailer for inspection at police checkpoints

Potential thieves know that there is nothing to steal

3 hours ago, Neeranam said:

Good point, but is there any reason it has to be the right hand door?

Because the left door is normal the inner door. 

3 minutes ago, Kwasaki said:

Because the left door is normal the inner door. 

I see, I thought it might be some superstition. 

It's so the driver can escape if the truck has an accident!

1 minute ago, Neeranam said:

I see, I thought it might be some superstition. 

No,  if you ever had a double rear door opening lorry/truck the right door was always the last to shut up the back.

 

At one time in London you had to show an open truck load you could cover up once out of London.