AFAIK, copper brake lines are illegal everywhere.
So what coils of tubing are they selling with all the brake pipe ends, that look like they are copper?
I have used that copper coloured tube everywhere.
Cunifer (or copper nickel, or cupro nickel, depending on where you are) has an appearance similar to copper, though slightly less 'red'. At a glance, it looks like copper, but as mentioned is a much better material. It is corrosion resistant, burst resistant, fatigue resistant, and much easier to work with than steel. In fact, it is such a good material that all high pressure (hydraulic and pneumatic) pipes on most of the world's 'cost is no object' navy submarines are copper/nickel. And they are working at much higher pressures and in much more extreme environments then the average automobile, and a single failure can mean the loss of 100 souls and a multi-billion dollar submarine, so only the best available is used. It's great stuff, and as Brian mentioned, steel brake lines should be outlawed as long as copper/nickel is around.