I can see both sides of this.

For myself, if it doesn't work, then it doesn't work and I shrug my shoulders and get on with other things. It's only one flight, after all. It's not my first and it won't be my last (at least in my own plans). I could put up with a not-so-good seat once in a while, and there's still the possibility that I can engage the goodwill of the airport staff to sort something out.

But if BA offers the service and publicises it as widely as it does, it really ought to work better than it does, because it's more aggravating to be offered it and to find that it doesn't work, than not to have the facility at all.