Well sure, John. Let's explore that issue for a moment.
When doctors form partnerships, they traditionally form a Professional Corporation or LLC. That document is usually dozens of pages long and is crafted by an attorney charging thousands of dollars for the service. Yet, even with all this protection, doctors will still disagree over the management of their partnerships, and sue each other on a regular basis. Even if they don't disagree, they employ individuals and accounting firms who's sole job it is to manage their money and their partnership, costing tens of thousands or more per year
Any other professional group would be the same. The civil courts are full of individuals that have disagreed with the management of their company or partnership to the point that they sue.
Musicians, on the other hand, rarely go to such lengths to document such agreements. If they bother documenting it at all, it's via email or some other sort of self-generated format that is virtually unenforceable. The money is self-managed, usually by a single member of the band. The partnerships that musicians form (you call it a 'band') rarely last for very long, and are usually pretty unstable. The pages of this board, as well as any other musicians board, are littered with stories of stolen and misappropriated band funds. You're posting in one of those stories right now.
So, please continue to pretend that you are on the same professional level with those professions you listed above, but reality is substantially different your assumptions.