A prime example for mandatory voting is Swizerland. But they have a 'direct democracy' (mostly) which means many laws are directly voted for by the population, not in the parliament.
America has a much bigger problem than lack of voters. First of all it is the more than archaic voting system from the late 1700s.
Secondly it is the abuse allowed in it: we have a district that voted mostly republicans and it is surrounded by mainly democrates? But last 4 year many 'democrates' moved into that district?
Lets just reshape the districts, so we are certain that we still have a republican majourity in said district.
In america before every election the 'ruling party' reshapes the voting destricts based on population data in the hope to 'manipulate' the outcome in their desire.
In every other nation that is considered 'voting fraud' or 'voting manipulation'. In the US it is business as usually.
Then comes the need to register for votes ... poor and underdogs, minorities etc. don't like to register.
Then you have the two party system (I really wonder why you laugh about China etc. with a one party system ...)
Then the 'electors' system ... it got changed at some point, but it is still retarded.
Then you had the Bush voting frauds ... come on, in every nation of the world, that is not a dictatorship, that election had been invalidated and Bush would be in jail and had haved no chance to even stay up for the 'Ersatzelection' ... but now 15 years later, who cares *shrugg*
Americans are really really strange regarding that ...
And from thst everything that is evil follows in the USA.
Who gets voted into office? Judges? Sheriffs? State Attorneys?
None of them is doing his job, they all only work to get reelected!!
Police cought one who has no aliby?
Sheriff: lets drop the hunt for the true culprit, lets focus on catching more idiots!
State atorney: How can we get him convicted? Hm, should be easy, he can not defend himself!
Judge: the harder I punish him, the more points I get for the next election!
How retarded is that? In germany the prime responsibility of a state atorney is to convict the right culprit, not a random 'victim'!
There are plenty of cases (in germany) where the state prosecutor in the end himself in the final speech plead 'non guilty' because it was obvious the guy charged was non guilty. Something like that can not even happen in the USA ... your law system is not much better than sharia, except cheating on your spouse is not punished (yet!)
Lets not even start with the idea that a jury in our days is the right thing to 'judge' a culprit.