As the title says, I believe that raiding building should be taken by surprise rather than alerting the base owners that you're raiding them. Not only that, many of the base/raiding rules are tailored towards the defenders anyway. Before everyone gets into an uproar over it, there's literally nothing inside of people's bases that are even valuable. Nobody keeps majorly valuable items laying around and they most certainly don't leave shipments laying in their base. The best thing you can hope for as an attacker is that you maybe find a printer or bitminer with money or bitcoins inside. These entities can be frozen with the physics gun which means that they either stay or get blown up (Considering occupying a base isn't allowed).
The only reason people raid others is because they're bored or they just want to kill someone. There's no value that comes from it.
The obvious reason this rule is in place to provide administrators with a time lapse indicator between people raiding to avoid violating the time constraints. This is not needed as the deaths between players can be used as a time lapse indicator as well which is certain when raiding bases.
I also do not believe this should be true for the police department. Every officer in the city should respond to a raid on the Police Department. This also helps to show who's involved in the raid. Raids on the PD are more important to regulate because a crucial class of players reside inside of that building.
This may also combat the problem between large and small factions. A smaller group of people may have a better chance at successfully raiding a large faction. If the large group doesn't want this to happen, it's very simple: Leave some people watching the base. This also falls on not allowing 15 people in a faction to rob you all at once as some may have to provide base security.