TheSagaContinues

Was there anything in the rules stating that vehicles and/or starships could only be damaged by heavy weapons at character scale?...

Not that I was ever aware of but don't forget that most vehicles and starships may have some relatively significant DR which may make many character scale weapons all but useless.  Throw up some SR as well and they may be untouchable.  Even if/when damage does get through it is likely to take a long time to eat up all of the vehicle's hit points; dealing "real" damage could require topping the Damage Threshold after overcoming DR/SR.

Shooting at an AT-ST (DR 10, DT30, hp 120) with a Blaster Rifle (average damage 14) would seem to take about 3 minutes of constant fire just to disable it.  Destroying will require getting it to zero hp with a shot that rolled 40+ damage to overcome DR then DT.  An AT-AT (hp 300, DR 20, DT 79) is mostly untouchable although you could occasionally scratch the paint with a great damage roll.

With that in mind it's often not really worth tracking those things unless it is very much an objective.