The answer being "Because you haven't booked in advance". :roll:
I don't think booking in advance is any cheaper on peak time trains first class.
Liverpool? It used to be a port when everybody and everything travelling to and from UK travelled by sea. Today it's an isolated city on a river estuary and the coast, with a subsequently limited hinterland. Because it has more of a past than a future it is populated by a lot of folk with big chips on their shoulders "who 'ave it 'arder than everyone else".