Some cultivars/clones are more attractive than others.

but bulbocodium hybrids such as 'Dove Wings'
and its siblings seem immune. I say *seem* immune, but it might be a matter
more of their earlier flowering, or it might be that they multiply strongly
enough that the bulb fly doesn't do much harm to them.
And again to demonstrate the fickle tastes of Merodon,
Leucojum aestivum seems [there's that word again] immune.

And some galanthus forms survive in good heart. The commmon double form of
Galanthus nivalis is not uncommon as a feral plant in locations that are
very
wet in winter. Perhaps the fly larvae drown?