Generally, from my time in a radio spectrum regulatory body, you start by enforcing EMR compliance at the importer/manufacturing level, so no-one can buy a new 900ishMHz baby monitor that would cause interference - either by regulating allowed transmitter power or just flat out verboten.

Then you respond to interference complaints as they come up, and commercial operators tend to be very vigorous in monitoring their spectrum that they're paying for, and can often pinpoint the location reasonably well already, and then the nice radio inspectors come out, triangulate it, and have a friendly talk.

Never really had a situation where spectrum that was regulated as "general user" (e.g., no need for a licence, but also no protection against interfering signals) and heavily used by by consumer appliances was modified to no longer be general user though.