Extract all individual addresses from a geographical area (includes an ethics question)

Currently based in Australia, I am conducting a social research through my university. I would ideally like to access a random sample of a population - determined by a geographical area on OSM or other. To really have a random sample (and not self-selected volunteers answering advertisement), the only way to do so would be to have a list of all postal addresses in the said area. And pro-actively contact the selected sample within those addresses.

Here are my questions :

• Is that technically feasible?

• If yes, would that be legal anyway? As it might be web-scrapping or considered intrusive

This question is probably going to sound very naïve - and I think I already know the answer - but I would like to confirm with more experienced people. To feel more confident saying that a 'strictly random' sample cannot be obtained ethically, and that I will need to go for a good representative sample instead.

Thanks a lot in advance for your help, Ann