Why didn’t Captain Marvel / Carol Danvers, intervene when Loki invaded New York with a Chitauri Army or when Ultron invaded Earth ?
The “Captain Marvel” movie takes place in the year 1995 and over the course of the movie we don’t get clues regarding the reason why Carol Danvers was not an option when Nick Fury ( played by Samuel L. Jackson ) – who already knew her and could have asked for her help – didn’t, considering that life on Earth as we know it has been threatened many times, for example when Loki ( Tom Hiddleston ) invaded New York City with an army of Chitauri, or when Ultron invaded the entire Earth.
At the end of the Captain Marvel movie, Carol Danvers ( played by Brie Larson ) gives back a pager to Nick Fury, a pager she took from him earlier in the movie in order to make some improvements. Now, Carol says, Nick can contact her even if she’s “two galaxies” away from Earth. Carol told Nick Fury that he should contact her only for emergencies. After that she uses her powers – which she got from the Tesseract – to physically move the space cruiser that takes the Skrull refugees outside the solar system to an undisclosed location.
The possible reason why Nick Fury hasn’t contacted Carol Danvers / Captain Marvel when Loki invaded New York, or when Ultra was a threat, might be because Carol was somewhere beyond contact. Which seems to be more believable than initially thought. Here’s why: in order to take the Skrull refugees somewhere where Kree warriors can’t find them, they should arrive somewhere beyond the Milky Way, maybe in a different dimension such as the Quantum Realm.
Although communication between our world at the Quantum Realm is possible ( as we can see in Ant-Man and the Wasp ) it is possible for Fury’s pager not to be capable of that.
It is possible for Captain Marvel to travel to the Quantum Realm thanks to the powers she got from the Tesseract. If a Infinity Stone might lead to the Quantum Realm, then it may also allow time and space travel anywhere in the Universe. As to the reason why Carol hasn’t returned to Earth from time to time to check if everything is alright, it may have something to do with the adventures she had after she left with the Skrull people.
We expected the story of Captain Marvel to be somewhat connected to the background story of Thanos, this because Mar-Vell and Thanos were rivals in the comic books so its possible for our hero to meet with Thanos in her journey, which may have taken up more of he time than we believed.