Photographers, DJs, bakers, florists are not religious organizations, they are for profit businesses. That's the big difference. They are business that are open to the public. The church has religious requirements for some of their ceremonies (such as first communion).

They are also often sole proprietors. Like independent software developers, they may not have a public "place" of business that is distinct from their home. What they do often amounts to contracts between private individuals and not so much businesses open to the public (like a restaurant or retail shop). I don't know enough about the law to say if this falls under a different set of rules, but it would seem reasonable that it might.