If you look at the demand side, it may look flat (ie demand is not sensitive to price) but within ranges. Industrial users will have cutoff prices (and may thus take out a big chunk of demand is prices go above a certain level). Some may have storage capacity and similarly drop out of the market at some prices (and become sellers). etc...
EDF has and had some interesting tariff arrangements with some of them - like interruptible supply pricing: such users get a low price, close to wholesale, but may be cut off (or have to pay punitive prices) at EDF's discretion, when it needs to deal with demand spikes. That reflects that they have processes that are not sensitive to cutoffs, or that they have alternative (and flexible) ways to get power at hand, and they act as 'peak supply' providers for EDF. In the long run, we're all dead. John Maynard Keynes
