"...yellow vests French drivers are obliged to carry in their vehicles..."
French drivers are obliged to carry the vests their vehicles in the case of roadside emergencies ( e.g., changing a flat tire ).
This is a signal to other drivers that someone is in need of help.
America suffers from YELLOW VEST creep. the plague is Americanized in the form of yellow T shirts. On a typical lunch day about a quarter to half of those eating are wearing the yellow
The Euro plague is here.....now
Yeah, a lot of people keep them over the back of the driver’s seat, so they’re handy if you have to get out. That’s what I do in my French car.