"if you are approaching a dog being walked on one of those leads, try to cross the street, and or give a wide berth to that dog. Assume that the human does not have control of the dog on that lead. "

I couldn't agree more!
I have as yet to meet a responsible pet owner that utilizes a retractable leash appropriately in a public space.
Personally, I can't stand the things. I bought a flexi when ZoE was a puppy, as my yard wasn't fenced in, and thought it would allow her s little more freedom to venture further afield and sniff around. One...it almost took finger off and left a bad rug-burn mark on my hand. Two..it was damn uncomfortable to hold. I haven't used it since.
I then bought a long training lead..I think about 25ft. It works great. It gives her freedom to roam in safe areas away from others. I would never think of using it on a walking foot path, as there she should walk heeled right right to me, yet others think its appropriate to use their flexis. Some people don't get that everyone doesn't want to interact with your dog in public, and no one should be forced to because you cant keep your dog under control. Although, now i think of it, the idiots that dont keep control of their dogs on flexis are most likely the same kind of idiots that dont keep control of their dog on a 6ft leash either