This has been common practice among carriers - to not include a means to access the FM receiver hardware on many devices. And, yes, carriers do have a lot of control over this, just as it is carriers that include bloatware on devices, above and beyond that included by some manufacturers.
As to radio interference, as I mentioned in the other thread, years ago (okay, decades ago) I had a Texas Instruments programmable calculator which caused massive interference to my bedside FM clock radio whenever I held it nearby. In fact, I could vary the pitch and tone of the interference, Theremin-like, just by slight differences in the position of the calculator.
So, I would consider it at least possible that improper shielding is the cause of the OP's problem.