Taking a fly is a visual thing; (they see it before deciding to take it) and lures are usually a visual thing too so comparing with corn on a muddy/silty bottom with Bream and Tench sending up clouds of mud and silt it is not really a good comparison is it.
That’s not to say that I don’t think artificial baits work; of course they do in some situations; either by sight, feel and/or taste (when flavoured). However although I have all kinds of artificial baits in various tackle boxes (maggots, caster, worm, bread, hemp, bloodworm, corn, corn skins, chum mixers and pop up bugs) I have never caught any fish on them at all (yet) and most of them haven’t even seen any water let alone seen any fish. I know they would work in certain conditions but I’ve never had any confidence in using them (so far) so I have always preferred to use the real thing; (except for lures and flies).
Keith