The Spanish voting system is not a pure proportional voting system, so first off the voters are not given full representation based on their votes.

There are 52 districts

Image to appear shortly

You see the number of representatives per each district, all different number of representatives.

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Then parties use a closed-list proportional representation party lists. This means that when a party gets enough votes for four seats then numbers #1 to #4 on the list get the seat.

In the Netherlands, the party list is open, which means if you and many other voters like candidate #20 on a list, and the party got just five seats, and #20 got more than required for one seat, then that person gets a seat and not #5 on the list.

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If we place all democracies on a spectrum, then I would say that voters in the USA (but also other voters in nations with empowered presidents) are more to the simplistic level of the spectrum, not delivering the voters all that much power in light of the results, and the Scandinavian countries (Sweden, Norway, Denmark) to the other side with voters' power fully optimized (give or take a nudge).

What disappoints me is that the US Constitution only declares how we must vote for the Federal level, so this can never be an optimization. Yet in the 14th Amendment, the States and local governments are ordered to optimize voting, but they are not complying to the US Constitution. They snub their noses, so we are limited by the prescribed Federal elections, and we are limited by the States refusing to follow orders that guarantee us our political freedom at State and local levels.