Cats five
You are correct, no one operating a private glider wants the extra costs of EASA 145 oversight as this oversight standard is disproportionate in terms of both paperwork and cost for private flying.
While Paul M says the both systems are similar and to a point this is true but unfortunately the devil is in the detail and it is that detail that drives up the costs of operating to EASA145.
EASA have now recognised that they over egged the pudding when they introduced part M for light aviation largely because they failed to understand anything other than the oversight required by the airlines. The result was an increase in costs that has decimated the GA industry and forced EASA to have a rethink ( I suspect because they finally realised that if the GA industry contracted any further they would all be out of jobs having killed the industry that they are employed to regulate ! ).
So we now see the introduction of Part M lite, a new far more appropriate level of oversight for private flying.
This will help the costs in GA but as flying the nations youth is essentially a function that would in the civil world would require an AOC the MoD requires the military equivalent of EASA145 maintenance so no direct cost savings can be made.
The up side for the MoD is that in the medium term part M lite is likely to invigorate the GA sector and the economy of scale is likely to drive down the cost of some of the equipment it will have to retrofit in the near future.