I don't disagree with you on this, but bear in mind lecithin is the fat of the bean with the protein removed. Obviously there would be minute traces of of soya protein left but not enough to cause an adverse reaction in the majority of soy sensitive consumers. This is the same reasoning that dairy intolerant people can normally eat ghee, as there is less than 1% of protein remaining after the fat is separated, and sensitivity/allergic reactions are to proteins not fats. I am not sure why you make such an issue of this? Soya allergy is rare in the uk as far as I am aware, I have never met anyone with it. I do not use sunflower lecithin personally as I am unable to eat the seeds without them causing bad indigestion so I figure I have an intolerance or allergy to them, it's also very expensive. I have never come across anyone with an allergy to soya lecithin. I would also add that my diet for many years has included absolutely no soya (other than the lecithin recently) so your theory really does not apply in my case. It is not difficult to avoid soya containing foods where I live, and I would have thought the majority of people on this forum are following a whole food diet?
You are referring to processed foods. https://farrp.unl.edu/soy-lecithin
"Many allergists do not even advise their soybean-allergic patients to avoid soybean lecithin when it is included as an ingredient on food products. From this practical standpoint, we can surmise that most soybean-allergic individuals do not react adversely to the ingestion of soybean lecithin."