Tested with Night in the server, bug is valid
SA-MP is shit and only allows you to control a vehicle's doors if there's nobody inside the vehicle, and it's been driven previously. I do not know why.
Well that's not a big issue really, only thing that needs to be fixed if possible is that dialogue reads states properly and ability to open/close all doors really triggers that like commands does, since everything works fine when using commands to open them, but for some reason state doesn't change in dialogue at all.
And for 2 seated vehicles, it reads like there is 3 windows and 3 doors for some reason.