To get the true intention of the game development you have to ask T-Prime, but I think it was a solution to keep the game mechanism as simple as possible. To relate it to the 2nd edition there were plenty of rules for vehicle and very detailed. Closed vehicles in the 2nd were extremely powerful and closed vehicles easy to stop (just kill the crew).
But the vehicles in UWZ are only support and not the main part of the game so you could say the pendulum is swinging into the other direction.
Fair enough. I guess it's all in balance and stuff, but i really would've wished for some differences between open and closed vehicles, at least regarding said environmental hazards (as well as weapons).
This is a little confusing but I will try to explain: The Environment classification of the weapon is for now most of the time just fluff. There were a time of discussion during the game development to give certain model types and armories certain weak spots (mentioned somewhere in the forum). There a only a few spots in the game where you can find the game mechanism like the Dragonswill Gun against A.I.s or Vulkans are vulnerable to radiant weapons.
Vehicles are immune to gas attacks, to ATS damage and to environmental effects (except the general effects) but they are effected by environmental weapons with normal damage like chemical sprayers.
I hope this will help.
Now this is confusing me even more. According to P.121 Environmental Weapons are declared as follows: "Weapons with this Weapon Effect have some kind of radiation, bacterial or chemical make-up that is highly toxic [...]. Each environmental hazard has an Attack Strength (or ATS) that represents the number that the affected model must roll under to avoid the effects of the hazard."
The way I understand this, is that weapons with the environmental designation in brackets don't do damage as normal, but rather have the ATS you mentioned in the DM column on a weapon's profile. This obviously messes up the immunity thing again, because most of the environmental weapons are indeed template weapons.
Now, the way you are explaining this to me, environmental weapons should do damage like normal, including the armor roll and not interacting with the Survival Training SA at all. But in that case, why does the Weapons
Values section describe the ATS rating? Also, maybe more importantly, why would thrown G-550 Gas Grenades work any differently from VX Nerve Gas Shell support munitions (and be immensely more powerful than AP Grenades at that)?