The reason that the Ecuadorian government and the people of the Galapagos take conservation seriously is simple: tourism. The Galapagos makes a lot of money from tourism every year, and the ecosystem of the archipelago is the main reason why. At one point, UNESCO threatened to take away the Galapagos’ World Heritage status, and from then on, conservation has taken a front seat.
To live in the Galapagos - even if you’re Ecuadorian, you have to have been born there, married someone who did, or have a work contract. The national park oversees all the tourism (the guides are all managed by them, and have to report on things like activities, the state of the animals, and rubbish found on each tour). There’s a limit on how many tourists can visit, and visitor’s bags are checked for contaminants as they leave each island.