I personally think that artists should have all money of digital sales. Not only "royalty". Unless there is some unusual effort put into whole project behalf of label. Lets say, label spends XXX USD to pay studio, mastering, artwork or such. Rather uncommon in noise. But in such case, one would think label gets something from digital sale of material it enabled to be done.
In typical case, where artists does basically everything, and label is the one who's job is just to manufacture and ship items - if there is no manufacturing, shipping and promotion at all, just "bandcamp page" where people pay - I'd say there is no label involvement to such degree it would justify even cut of money. Rules of the mainstream business is totally different, as labels pay the bills and make investments and recoup vast amounts of money spent in advance. Digital noise sales would be entirely different thing.
But after all, when you really look at it, then how big could be digital sale income of noise? I recall great story of one higher profile noise artist getting paid for the royalties of iTunes sales and after time consuming calculations of what items sold and who gets what and the change thrown into envelope wasn't worth of stamp to deliver him cash. For reason or another, couldn't take transfers at the time.
I, as label, don't care. Every band is free to use their album at their own bandscamp or throw into youtube as full album if they feel like it. I don't have time or energy for such. Not for calculating who gets what and not even uploading things. Even uploading any of my own works seems bigger task than "releasing cd".