In Australia, voting is compulsory, so turnout is in excess of 80%.
There is no requirement for IDs when voting, just making sure your name is crossed off the list in the seat you're registered for. This obviously means that you can, illegally, vote twice at two different locations, but the system will pick it up (when they scan the registers)
I'm not entirely sure, but I think the election officer can request some form of ID if they suspect foul play.
Anyway, it is possible to cheat, but the percentage of rejected votes is so small that there is no reason to change the system and increase the costs associated with it.
I guess, because the voting is compulsory hence a large turnout minimises the effects compared to a voluntary voting system where the turnout is low and the percentages become significant.