My opinion on the matter
Medical Hemitts Missions don't need to be removed but instead replace with a system that persuades trolls not to use them, but instead help with the detection of trolls that are using the mission to cause grief on the server.
If this mission AKA - Centrelink's Legal truck mission is removed we are only removing another role / activity for Civ players to do. ATM the only LEGAL roles a Civ can do is COPPER, IRON, DIAMOND, OIL, SAND and a few others and even still these are high risk jobs as many rebels occupied this areas for their own gain.
To use the system that police operate with when detecting a illegal truck mission. So create the same system but for legal truck mission. When it comes to trolls and the missions the biggest problem we have is finding who it is, the simple method of checking to give money trick doesn't always work when there are a number of people around.
And / Or
What a few people have already said is that a cool-down timer might also assist with the identity system can slow down the trolls using the system.
so what i propose is too add a system that identifies the users of the vehicle. When the Mods/Admins have names and can have evidence to support it,with this system it extremely difficult for a troll to evade staff and to trolling other players.
But gentleman please note that this will take a-lot of effect from the dev team (@envy) "If" this done.