Saeviomagy
Adventurer
The "specific rules" do not say that.
AV says that vehicles can be attacked and damaged like other objects, that like other objects they have HP and defenses, and when HP goes to 0, the object is destroyed.
The DMG says that objects can be attacked and that "damage is damage". Thats what it actually says. Immunities to attacks or damage is for unusual items only.
Damage is damage, but targeting is targeting. Please feel free to point out any damage powers that you've found which do not specify that the power targets creatures (whether enemies, allies, or just creatures).
There's a clarification in the errata that specifically states
“Some powers include objects as targets. At the DM’s discretion, a power that targets a creature can also target an object, whether or not the power lists an object as a potential target.”
So - the fact that damage is damage is irrelevant. Your power almost certainly targets a creature or creatures, so any use you make of a power on an object is entirely at the DMs whim.