Stupid question on brake line.

The springs on the brake lines is called armor. You'll find it in areas where it is more exposed to damage whether from road debris or routing (between a frame and body, close proximity to moving parts, et al...)

The reason you have coils by the master cylinder is for flex and vibration. The lines are made out of steel and will work harden over time with flex and vibration. It's more cost effective for a manufacturer to make a line with a few coils in it than it is to make an entirely separate flexible hose. Yes, our cars move like living animals. Watch your master cylinder while having someone step on the brake pedal. How many times do you step on that pedal during the day? Add in body flex and twist and you get the idea.

Some cars do it more than others. When I build custom lines, I tend to forgo the coils. Most of the cars in our hobby don't get the long term DD duty they were originally intended for anymore, so I lean towards eye candy when I do them now. (I still try to put some stress relieving bends in more hidden areas).