D* is required to stay on the ladder when doing a roof install now, been that way for multiple years now.My understanding is the installers will no longer go up on a roof due to new OSHA regs, and there's a bunch of them, from the safety gear you're required to wear if you're within 6 feet of an edge (most dishes I've seen mounted on a roof) to how high a ladder you're legally allowed to use whether portable or permanent (2 different rules). If you don't follow the rules and you get injured your insurance may not pay.
OSHA's New Fall Regulations to Affect 112 Million Workers
Also, they are suppose to only install over a Non Living area, all though I don't know how strict they are about that one.