hundreds/ thousands, think: Reggae
I know this might be hard for some R&P.
Almost every reggae song is protest. Bob died in '80, but many greats carried the flag through the '80s:
Black Uhuru, Steel Pulse, Burning Spear, Sly Dunbar, Peter Tosh, Greggory Issacs, The Abyssinians, etc..
I know they were not hits on the radio, but hard hitting, angry, powerful, political. good stuff.
edit: Bob Marley's final album was Uprising, 1980. On that album was 'Redemption Song.' There is an '80s protest song everyones heard, and proves my point also.