the swag an old time swaggie or swagman wore is a different beast to the things sold nowdays as swags
It used to be a canvas sheet ( if they were lucky ) to serve as ground sheet / wrap over if the weather got wet or snowy .. a couple blankets and whatever else could be stuffed into it for safety and easy(ish) carry
now days there is a tailored , zippered canvas ground sheet / cover with a matress of sorts , and a couple blankets or more usualy a sleeping bag
it is used a lot in stock camps , by people working outback and traveling by vehicle , they are very common sights on backs of trucks in the more rural parts
the why of using a swag vs tent is simple
you roll out your swag , climb in go to sleep , wake up roll it up , move on .. no setting up tents then organising gear inside it .
they last .
they really do , they are used as daily sleeping gear for a hell of a lot of station hands , ringers , jack / jillaroos , and even more Aboriginal folk who live out of them .
I have used a swag for 6 years or so , gifting it when I was done , it had a lot of life left in it . my girls dont like camping "that rough" , it doesnt allow for privacy to get dressed , it is sleeping gear , lay it down closeish to the campfire , use it to sleep in , roll it up when you wake , kick it outa way and go about the day , inside it tho is your gear that you want to keep safe too , i have seen rifles , hand guns , stickbooks , knives , computers and cameras , all sorts of gear come out of a swag over the years
I dont have one at the moment , havent for a while , but Id choose one any day over a lot of other sleeping gear . Especially the modern swags , yes they are car camping gear , but for the ease of unstrapping and kicking it to roll it out and presto , bed WITH mattress .. and usually a waterproof sheet to pull over face if needed .
this is my take on them tho , and very largely based on my own opinions and experience .
YMMV , i know they are not common in urban areas , they have no real use for people who go out once a year or so , they are just too bulky . It takes being used daily , for extended period of time to apeciate them , at least it was my experience anyway