@sidereal @mekkaokereke @mickeleh as an Australian I can confirm, we do have the option to do "mail in voting" if we want, usually referred to as a postal vote. I'd like to point out that most of us don't because it's easier to do in person voting for a large portion of the population.
I have a polling place that's always setup about 12 houses up the street from me. Most more urban locations will have a polling place no more than a couple of miles apart. If I go vote at a more off peak time, there is no line, takes me a few minutes only. Some polling places might have a sizable queue at peak times, but waiting in one for more than 30 minutes would not be typical.
There are other things that help such as employers being required to give time off to vote on election days (its a serious offence not to) and being able to vote at any polling place you choose (I.e. If you are unexpectedly out of town it's no problem, you just vote wherever you are).
Postal votes are frequently used by people who are either in remote locations (Australia does have plenty of that), people who are out of the country or state or have some sort of disability that makes postal voting easier. Anyone who wants to can though.