Parliamentary systems don't imply proportional representation necessarily. Commonwealth nations like Canada and the UK use the Westminster system, and use a first past the post system derived from that tradition for example. It simply depends on the country and who decided on the details of the electoral system.
They have exactly one district, right? They simply don't have enough liberals there.
Wyoming is a shit state tho. Actually scratch that the nature part is great. Too bad we all can't move there and take over two senators. Only need a few thousand voting age non fascists to move in right?