The most obvious things you’d notice in my car boot are 6 big cardboard boxes/cartons.
I’ve found shopping bags to be just one more useless unnecessary environmentally damaging item.
The cartons have one side cut out of them & items from the groceries trolley just get bundled/tumbled into whatever seems appropriate. e.g. Frozen goods go together in one box then once home that box/carton goes straight to the fridge/freezer.
The other thing I do with these free retrieved*(recycleable) cartons from our big hardware store is to cut a circular hole at each end near the upper lip for my fingers ( instant handles )
My vehicle is a shooting brake or station waggon/estate car, so no boot as per a regular saloon car, but in the rear of my pathfinder 4x4 is LD’s survival kit inc air compressor and temporary tubeless repair plugs. Oh yes and my jump starting kit of 6M long leads and a regularly checked & charged power system
The usual jack, spare wheel, and tools for the changing thereof…Plus, jump leads (more for me than the car ) An umbrella that has never been used…It usually rains while returning to the car, and if it’s raining before hand…I don’t go…
And last but not least…Two plastic boxes that fit comfortably into a Tesco trolley. No shopping bags here. Just fill em’ up in store using the hand scanners and take em’ out at tother end…
I carry jumper leads but I have a 120Ah aux battery in the back that can start the car if the starter battery dies. It is charged by the alternator or a 110watt solar panel on the roof, it’s an AGM deep cycle battery so starting the car won’t do it any favours but in an emergency…
I would think that a failing vehicle while travelling in Australia’s outback would be almost certain death. If I lived there my boot would be similar to yours Bruce.
I have never had to use that battery for anything other than running the fridge and some LED lights. It will run the fridge indefinitely with only input from the solar panel on the car roof, no need to run the car engine.
However I also have a folding 160 watt portable panel if the car or camper is parked in the shade for an extended period.