Not to mention that probably a majority of the electric gas and water meters in the US operate in the 902-928 range.

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.

Wireless microphones used by newsies or other production types used a frequency range that was deprecated. Your gear didn't just magically stop working. The places you were allowed to use it got really small. When a crew works an event like a sporting event, all wireless devices and their frequency must be logged to prevent competing signals between crews. If you show up with the old stuff, you're pretty much laughed out of the room and denied use of the gear. At less regulated places, your use of the equipment will just be subject to interference from other signals that are now using the bands. If your use causes interference, you can be subject to appropriate penalties