H500,
We used to be required to do likewise in the Whirlwind, prior to the Gazelle, albeit with Decca rather than MiniTANS. Those stats were probably never compiled and in any case, they would not really be directly comparable to the civilian world. As a military pilot you would have been given the benefit of recurrent instrument flying training (a minimum of 12 hours per year during my time).
If civilian RW were given carte blanche to fly in IMC, logic says that inexperienced pilots would begin to suffer LOC accidents in IMC due to their inexperience and lack of training.
Also, you don't need stats to realise that an unpowered helicopter won't fly too far, hence the requirement to be required to fly over notified routes in a SE aircraft, such as the London Helilanes. Twins are allowed to fly off route, singles are not.
There has been talk of the lack of duplication of tail rotors and driveshafts. In an ideal world, everything could be duplicated, but at high cost, in more than one sense. The regulatory requirement for duplication of power plants comes from the fact that engines can fail for a whole variety of mechanical reasons, as can tail rotors, but they can also fail because of lack of fuel, lack of oil, or from FOD ingestion, icing and so on.
If you clout your tail rotor or main rotor whilst manoeuvring near the ground or obstructions, it matters not a jot how many engines you have, the result will be similar. If you run out of fuel or lose control in the air or have a CFIT because your IF skills or planning and airborne situational awareness aren't up to the job, likewise.
But having more than one engine allows more redundancy and duplication of systems by design and an extra level of safety in those respects, at least helping mitigate some risks. Which is the way aviation should be heading, not backwards as some protagonists here seem to demand, mainly out of lack of experience or common sense.