First past the post
Suppose you had a very simple country of 3 seats (A, B and C), each with 1000 voters and 2 parties (X and Y) for the country.
In seat A, party X gets all 1000 votes and party Y gets 0. Then X has won. X got more than Y.
In seat B, party Y gets 501 votes and X gets 499. Then Y has won. Y got more than X.
In seat C, party Y gets 501 votes and X gets 499. Then Y has won.
Y has won 2 seats and X has 1 so Y is the overall winner.
X got 1998 votes (1000 + 499 + 499) and Y got 1002 votes (501 + 501), but X still lost.
But that’s the way the UK system works.
If you then said oh proportional representation, you could argue that X got (roughly) twice as many votes as Y so X should get twice as many seats as Y. X will have to have 2 seats and Y will have 1.
So X gets seat A.
Y gets seat B.
X has to get seat C, so X can have 2 seats, even though the majority of people in C did not want X.
There are so many possible systems and we’re sure that each has flaws. There are systems where people have to vote twice (bonjour mes amis) for example. Maybe it’s possible to design a ‘perfect’ system (whatever that may mean) but it might be so complicated we couldn’t understand it.