You do not seem to know the business model very well.
Commercial photography (including social events, of which weddings are a sub-set) has been part of how I make a living for about 30 years. I've watched markets and business models come and go. I know a lot more about it than you do.
Wedding photographers usually have zero and sometimes even negative profit selling photos to the newlyweds once you take into account equipment and consumables.
If by "wedding photographers" you mean "amateurs who don't need to make a living at it," then, maybe.
The profit is achieved by selling copies of the prints to people attending the wedding itself.
Are you writing from some alternate universe, or perhaps through a wormhole connected to 1978? Like I said, this is something that you don't know much about.
A lot of these photographers do contract work for advertisement agencies as well. In this case the client gets to own the digital files.
The fact that you're not even using the right words, here (hint: it's not about the files, it's about transfer of copyrights, or work for hire, or licensing), suggests that you need to study this more.
The difference is the client pays a lot more, a whole lot more than a wedding couple is willing to pay.
There are wedding couples who pay $300 for a full day's work with a DVD and full rights, and there are wedding couples who pay $30,000 for what amounts to a small movie production company to spend the entire weekend with them - and what they get is a limited license to a version of the finished body of work. Likewise there are commercial clients who write work for hire contracts (where the photographer never has copyrights), and those that merely want to license an image or two from the entire shoot.