It's a protection under copyright law. The "author" of the work generally owns all rights because they created it. Exceptions exist, such as work for hire, but that is when it is an employee not an ind. contractor. You are contracting with someone so they retain the copyright of their creative work and you are paying for a specified use. They can transfer rights to you if you negotiate it upfront, but I'm not sure that is very common. No one has ever asked me to transfer rights.

Clients don't usually generate the contracts which may be why you are finding more geared to the trade. However, you can use any contract as a starting point for negotiations or have a lawyer review them on your behalf. Just be sure to sign only when you understand and agree with everything in writing.

Regarding ownership of design: As an attorney, I would say you should contact an attorney if you really want an interpretation of your specific contract--anyone else is simply not qualified. That attorney would also need to look at the entire contract, not just one paragraph that might act as exception to others. That said, it would not be unusual for a contract to state that you do not retain ownership of the product. Nevertheless, you're likely receiving rights for as much use of the plan as you will need, along with copies for posterity, so it might not be a bad thing. If the contract really limits you in an unexpected way, then it really might be worthwhile to contact an attorney to look at the entire thing. Generally, the language of a contract is binding according to its plain meaning, but there are often other considerations and remedies available.

Ah, I see. You've calmed my fears AND persuaded me to run all contracts by our lawyer.

So helpful. Thanks to you both.