@Wannikea ********
Haha. Well, I prefer predictable rules. I'm far from old, but when I do get to that age, I'd hate having to deal with tons of bureaucratic nonsense.
Now with that stated, taking out a Thai car is generally straightforward enough - it's usually the neighboring country that puts in place roadblocks (except at the Chanthaburi crossings, where a military permit is required to take your vehicle out and Thai customs is known to block Cambodian owners of Thai vehicles because they're afraid they won't be brought back in...absolutely silly and discriminatory). On the other hand, Cambodia until relatively recently, generally banned Thai vehicles from entering via Ban Laem just in general, regardless of who owns the vehicle.
Thai truckers get the short end of the stick when going to any neighboring country. Fuel trucks aside, Laos no longer permits Thai trucks to travel further than a short distance from the border crossing entered. Meanwhile, Vietnamese and Chinese trucks ply Lao roads in their thousands.
Cambodia also has restrictions on how far Thai trucks can travel from the border - but Vietnamese trucks have pretty much free reign.
Malaysia bans entry to Thai buses, vans and Thai trucks - except in rare cases of perishable items, but generally, Malaysian trucks enter Thailand to pick up these goods and then transport them to destinations within Malaysia or Singapore. Sometimes you see Thai registered trailers within Malaysia, but the trucks pulling them are always Malaysian registered without exception, despite Malaysia and Thailand driving on the same side of the road.
For Thai cars going to Laos via Vientiane - they're back to restricting them to 15 days (although this is extendable later), meanwhile, in the reverse direction, you can easily get 30 days if driving a Lao car into Thailand right at the border.