No, there is no mandatory voting in these nations.

For Sweden, the voter turnout was almost 85% in 2022.

For the Netherlands, the voter turnout was not yet 80% in 2021.

For Spain, the voter turnout was about 72%.

For the USA, the voter turnout (an all-time high I believe) was 66% in 2020.

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When going to the voting booth, it helps knowing that your vote translates into an actual outcome. It is very difficult to vote in Sweden or the Netherlands and have your vote go to waste. Near impossible.

In the USA, people have voted their entire life never receiving the individual they voted for. As shown for the US Senate, more than 40% of the voters went home empty-handed.

The USA is not a democracy because in a democracy the voters are represented. We have a clash in the voting booth between voters.

Guess who benefits from this setup?

Those in the seats of power (both in the actual seats and behind the curtain).

Change is much harder to put in place when voters compete with voters for the win. So many people end up being muted, cannot express themselves. And when they are successful expressing themselves, then they were herded through one of just two doors. There is no third door to enter in the US voting system because it is always about one person winning.

In Sweden, the Netherlands, and Spain, the voters have a much better choice.

It's like flipping a coin in the USA, you pick heads or tails. You win if you are with the majority

It's like rolling a dice in a real democracy, you pick 1, or 2, or 3, or 4, or 5, or 6. You always get your pick. The entire pie of seats is cut up based on all votes.

That is why it is called proportional. The same portion of votes is reflected in the same portion of seats. Ten percent of the voters receive ten percent of the seats.

Thomas Jefferson was the first to devise it. In Europe, Victor D'Hondt from Belgium was the person to more or less do the same about 100 years later, and Belgium was the first nation to vote proportionally (Belgium does have mandatory voting).