As far as I can see, the party structures are working as they are supposed to work in the USA and UK. It is about beating the other party for power. In some ways, we have not really evolved from our feudal past, as the various aristocratic houses were trying to usurp each other.
The people inside the parties are constantly jostling for status, influence, and power within the party. This dysfunction eventually spills into government operations and society-at-large.
Bettering society is a of distant secondary importance in the political party. We need to really understand that fundamental nature of political parties. They are not humanistic in most senses.