Originally Posted by
Habis
Actually, the US government has very rarely taken direct action against mutants.
During the 80s NotRonaldReagan!'s government tried to pass a law to force mutants to register their powers arguing that it was similar to gun control, put pulled back when Cyclops's X-Factor defended New York against Apocalypse. At that time most X-Men were hiding (Storm's team were believed to be dead, Cyclops's team were passing for non-mutant superhumans), Xavier was in space fucking a bird, Magneto was running the school and training the New Mutants, and the most notorious and popular mutant superhero team were... Mystique's Brotherhood of Mutants, who were acting as enforcers of the US government while pretending to be heroes... These were confusing times, and non-mutant heroes were pretty confused themselves...
The government secretly sponsored Bastion's anti-mutant organization Operation:Zero Tolerance, but they hit the brakes in the last minute and sent SHIELD against Bastion when they realized Bastion was hunting and executing US citizens.
Mutants were mostly left alone during Civil War I. Other superhumans were arrested and incarcerated, but not mutans.
The Avengers attacked Utopia during the Avengers vs X-Men event, and the government condoned it, but it was because Wolverine and Beast had told them that the Phoenix would destroy the world.
Norman Osborn's Dark Avengers attacked Utopia, but it was mostly because of Osborn's hurt feelings (his team of "Dark X-Men" dumped him and returned to Utopia).
During Secret Empire the mutants actually struck a deal with Hydra and were left alone.
Most anti-mutant action is taken by secret agencies or terrorist groups. Why doesn't the 4F or the Avengers do something against them?
Well, they sometimes do, but these groups are secretive, and the X-Men tend to meet them before any other superhero group because these enemies target the X-Men and their relatives and friends.
The Avengers try to avoid getting into conflict with the government; they know there are lots of shady agencies doing lots of shady stuff, and not only against mutants, but also doing stuff like kidnapping and dissecting aliens or creating superhumans or spying on heroes, but if they fought the government that would hinder their ability to fight the world-ending threats that are their specialty. They still fight against these shady agencies when they discover them doing something illegal, and publicly denounce them, but they don't go out their way to find what the government is hiding...
As for 4F, they avoid politics and government stuff like the plague. They involve themselves mostly with cosmic stuff, and when they fight common villains is usually because these villains attack the 4F or make a very public mess in New York.
Also, you have to take into account, ALL heroes are very reactive... they mostly wait for villains to attack, and rarely track and hunt them, scouring them from the root. Even the X-Men rarely investigate who is building Sentinels, or hunt for villains like Mr. Sinister.
As for the Avengers in particular... they are famous for not taking care of their own... like, when one of their own disappears or is kidnapped or brainwashed, they mostly sit down and wait for them to appear on their own... they allowed Marcus to leave with a brainwashed Carol Danvers, they allowed the Presence to leave taking with him a brainwashed Red Guardian, they allowed the Wasp to marry the guy who claimed to have killed Hank Pym, and when said guy turned to be an insane Hank Pym, they didn't try to make him receive mental treatment; they didn't seek Wanda after she disappeared (save Hawkeye, who did some token effort), they didn't seek the Wasp after she disappeared (save Hank Pym), they didn't move a finger when the Avengers Academy students disappeared (save Hank Pym,again...), they never tried to help Bruce Banner control Hulk (but they have exiled him from Earth or captured him or killed him a few times...).
So you see, it's not that they don't care mutants... they just treat mutants like they treat their own...