Is it true that snakes can be easily found inside Australian houses/apartments?

Assuming you are talking about wild snakes and not pet ones, it does happen but you would have to be unlucky. I see them in my yard every year but they are just cruising through. Usually late spring after hibernation when they are on the move. I have had a peninsula brown in my pergola area but not in the actual house.

Generally people get biitten when trying to remove or kill them. Better to leave them alone.