Perspective though, The Southern parks have better transport links to London (ie 8 million potential customers from Central alone), they are also cheaper to run being smaller and require less staffing budget and therefore are able to budget 5pm closes. Towers has never had that kind of flex, in all my time visiting theme parks, Towers has always had these restricted visiting hours. The Smiler incident only really highlighted how much more restricted they can go.
That isn't reality though. Even on 5pm closes, a lot of people have already left and the park is dead, people wishing to avoid the rush hour traffi, the only exception is when its very hot. That's when the park should stay open later. In an ideal world, yeah the park would be fully staffed and all rides open, full availability, 6pm closures. But we don't live in that world.