Some people are pretty resourceful. Several years ago there was a bad accident in front of me. A young boy in the car had a nasty impact wound on his head that was really gushing. I managed to stop the bleeding with pressure. Someone I never saw handed me a freshly opened bag of white cotton T shirts. Great improvised compresses. Someone was bring then home from shopping I suppose and repurposed them.
Feminine hygiene pads are outstanding for that purpose as well.
I was on a jobsite a few months ago and some guy got his hand caught in a claw bucket of a bobcat. Probably broken. After treating for shock, I used 3-4 trash bags to pressure wrap it and splint it tight to his body so his crew could take him to the ER.
The crew had no real first aid kit. A box of bandaids and an ice pack. Now, they just have bandaids.