Answering the question in the title of this thread isn’t quite that simple because people are different. There are clients who have a strong idea in mind and there are clients that have no idea at all. The designer has to adapt their approach according to this. If the client strongly insists in something you shouldn’t impose your opinion on them. If your arguments are stronger than theirs (and I mean arguments, not opinions) then I guess even they would realize it eventually but you have to make them clear why your proposal is better than their idea.
Now, if I was to comment on the design/problem in question, I would really say that a white background (or a solid color in geneal) is actually the better choice. In this case a photo as background is indeed distracting. You already have a big photo as main image and another photo in the background is really confusing. So, go with a flat color; in this case I even think plain white fits great.
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