Compulsory voting (well it's
not actually, you can attend the booth but not cast a vote) ... is a good thing.
Just imagine a system where someone could be elected as leader of the country with only a small percentage of people actually voting?
How horrible. Oh, wait ... that happened in the US.
As it happens, in Australia, despite people grumbling and moaning about having to vote, the vast majority actually do have an opinion. This is evidenced by the small percentage of "informal" votes. (Roughly 5%)
So it seems that the overwhelming majority of people do actually have an opinion about who they want to elect.
There is the "donkey vote" factor too, but it is impossible to be
sure about the extent of that since no-one can be sure that someone did a donkey vote - they may have chosen their vote in that order.
Anyhow, non-compulsory voting is bad because it allows nutters to gain power on small percentages of votes and it also favors the "well off" because they are more likely to vote in bad weather for example, compared to those who don't have transport of their own.
Not to say that the system can't be improved of course ... like the "preference deals" done between minor parties - often "brokered" by some ratbag middle-man.
That stuff should be outlawed.