I expect the lift was waiting to access the ferris wheel. . It beggars belief they could place it there, given the type of aircraft likely to use the grass. Safety is meant to accout for likely possible outcomes esp at a airshow. Reminds me of the Jules Bianchi death in F1.
Yes pilot may be at fault for deviation of straight ahead, but this is stupidity, might as well have landmines to punish mistakes.