I've been "down" 5 times on a street bike. None of them involved cars. Two were at less than 30 MPH. Three were at less than 5 MPH.
I've always worn long sleeve shirts or a riding jacket. Boots, trousers, gloves and a full face helmet. I rode like that before helmets were the law in California. I've never worn shorts, sandals, etc. I cringe when I see people dressed like that.
All the time I see some guys riding a rice rocket in a $600 Shoei wearing shorts, T shirt, sandals and no gloves. Riding/perched on the back is his girlfriend/wife in a $600 Shoei, no gloves, high heels and a short skirt.