nobody does DWC on a large scale. its not cost effective labor wise or cost wise. weed growers use this system because a small number of plants yield a profit.
the larger the scale the hydrosystem the simpler it tends to be... most large scale systems are just fertigation setups that push fertilized water out out to drip emitters. the mediums can be anything from rockwool to rice hulls.
NFT can be used on small rooted plants like lettuces etc, but not shit like peppers.
hydroponic soil less systems can be very cost effective, its just a matter of how you want to grow shit.
you can pull off a little 100 plant CRF grow, with a tap water irrigation system for like 300 bucks easily... not including the medium. a sack of osmocote pro is like 100 bucks at my local place.
going up a little more for like 600 bucks you can get a pair of dosatrons... good for thousands of plants.(they dont really make any "small" dosatrons).
you can DIY a system together like i did... and simply pump nutrient solution from a reservoir. good pump will be like 100 bucks + irrigation timer and irrigation emitters etc ... probably 300 bucks or thereabouts.
nutrients dont cost much. bottled nutrients do, but nobody with half a brain uses bottled nutrients at large scales. it costs too much.
what people use is sacs of fertilizer salts.... calcinit, MKP, DKP, DAP, potassium nitrate... chelates, epsom salt etc. these are far far cheaper on a per gallon basis.