Radio gets revenue from advertisers, just like Firefox gets money from Google.

Private For-Profit Radio Stations get revenue from advertisement. But Sony and JBP and Bose aren't advertisement based. Mozilla isn't a content provider, its an application developer.

there’s no “one time payment” that could support a radio station indefinitely

There's no "one time payment" that supports radio manufacturers indefinitely, either. So the companies develop new models and improved features, then retail them as replacements to the old device. But I've got an old machine from the 1980s that picks up AM/FM just fine. Sony isn't out of business because it continues to exist.