No way that's true. Wonder if they're getting selection bias, ex. the 90% of the people who are willing to take an unsolicited survey on their land line phone.
I can't back up the 90%-of-people claim, but as per the industry-accepted audio listening diary survey, a giant 74% share of audio consumption comes from AM/FM broadcasters [1]. So 90 percent is very possible.
I got a diary from Nielson for radio stations I listened to. I never listen to radio so I entered the stations and programs I wanted to be successful, rather than the ones I was listening to (since I wasn't listening to any of them). (so NPR and the local public radio station got a little boost).
Yeah, there was a lot of "vote for your favorite station" activity when the Arbitron/Nielson diary was used as the main system.
I was working at a station when they switched from diary to the electronic PPM system. The station's cumulative numbers jumped 3-fold that month-- we had no idea that many people were listening.
[1] <https://www.westwoodone.com/blog/2022/11/21/edisons-share-of...>