Reactive armour needs to be attached to thick armour. If it’s attached to non-armoured things, it will do just as much damage to what it’s attached to as what it reacted to.
Any civilian truck covered with reactive armour is a death trap, and any soldier who knows anything about reactive armour will target these vehicles with the cheapest weapons that will trigger the armour. This is an example of the enemy going out of their way to get killed.