You asked what brake line material is on CRVs and of course they will eventually rust, Honda has the lines epoxy coated to delay corrosion but they will succumb to the elements and road salt. C70600 copper alloy brake lines has been DOT approved but you have to be careful as to the supplier. Like everything else you buy online there are suppliers that may sell tubing that probably don't meet DOT specs.
Edited: Note to others reading this, regular copper tubing is illegal for brake lines. It simply doesn't have the burst pressure rating and it more easily stress cracks unlike copper nickel alloy tubing designed for brake line use.