Our sides are within a meter of our boundaries and so we have to demonstrate reasonable precautions to prevent fire spreading from one property to another.
Whilst they aren’t technically enforceable it would seem odd to me to be willing to spend money on things like a robot vacuum (a similar cost level) and not on something that might save a life. In my mind once a fire is bad enough to operate the strips the house is in real trouble, the key drive is to slow stuff down long enough for everyone to get out and the fire service to prevent spread between buildings.
As for positioning, I’d agree that they will be less effective at ground level, but I’d also argue that one wouldn’t want a single strip atop a 6m cladding ‘chimney’.