Why does every country still teach heliocentrism if geocentrism cannot be disproved?

Because heliocentrism is more than an astronomical model. It is the foundation of the Copernican Principle, the philosophical claim that the earth and man are nothing special, and every institution that trains, funds, publishes and employs scientists has its career and its worldview invested in keeping that claim intact. Start by noticing what is actually being taught. The claim is far bigger than "the earth goes around the sun." It is what the schools call the Copernican Principle, also known as the Cosmological Principle or the Principle of Mediocrity, and the principle is simple: it tells us we are nothing special. Carl Sagan put it in the standard form: "We live on an insignificant planet of a humdrum star lost in a galaxy tucked away in some forgotten corner of a universe in which there are far more galaxies than people." Stephen Hawking celebrated what the Copernican revolution accomplished: "Gone is our privileged place at the center of the universe, gone are eternity and certainty, and gone are absolute space and time." Pascal, three centuries earlier, described the same vision less cheerfully as "vastness and more vastness, never ending and never satisfying, filling us with doubt and horror." That is a metaphysical commitment, not an observation. And you can watch it operating in the open. When Hawking faced the fact that the universe looks the same in every direction from our vantage point, which straightforwardly implies we are at the center, he reached instead for Friedmann's second assumption, that it would look the same from any other galaxy too. He admitted there is no scientific evidence for or against that assumption, and said we believe it "only on grounds of modesty." So the choice between the two explanations is made on the basis of a claimed human virtue, not on data. That is the whole enterprise in miniature. A man is reviewing the same observations I am reviewing, and he picks the option that removes the earth from the center because he has decided in advance that we must not be at the center. Meanwhile the data keep pointing the other way and getting explained away. The cosmic microwave background, which pervades the whole universe and is supposed to be a relic of the original creation event, turns out to be aligned with our solar system: a dipole whose plane tracks ours, then a quadrupole and an octopole, also planar, also perpendicular to the earth's path around the sun. The odds against any one of those alignments arising by chance are worse than one in a thousand. Astronomers have nicknamed the phenomenon the Axis of Evil, which tells you how welcome it was. Their published response is that these are either bizarre coincidences or a signpost to something more fundamental, and then the subject is dropped. As similar coincidences pile up from every field, the only people who will not see them are the people who refuse to see. Then there is the ordinary human machinery of an established theory, which has nothing to do with truth and everything to do with employment. Tom van Flandern, who was a card-carrying member of the scientific establishment before he started noticing how much of what he had been taught was wrong, listed exactly who has a stake: editors and referees who have already made decisions based on the theory, funding agencies that have paid for research presupposing it, instrument builders and experiment designers who have spent their careers testing ideas that spring from it, journalists whose publications have promoted it, teachers and interested laymen who learned it, were impressed by it, and have no wish to learn or teach something new, and students who need to finish their degrees. He also described the tactic used against dissenters: alternately attack and ignore them, and discredit their motives or their competence, until conformity is achieved. And he identified the modern trap of specialization, where a model survives because many authorities support it, none of whom has the expertise to criticize it as a whole, and all of whom have complete confidence in each other, so the thing rolls on because "so many experts can't all be wrong." None of that is unique to cosmology. The literature on scientific misconduct, peer review failure, unreplicated experiments, data massaging and the pressure of government funding is extensive; Broad and Wade's Betrayers of the Truth catalogued it decades ago. I point this out not to say that all scientists are liars, but to answer the assumption buried in your question, which is that if something were true the institutions would teach it. They would not, not if teaching it cost them. And the model itself is not in the position people imagine. The geocentric system is not refuted; it is equivalent. Newton himself, at the end of the Principia, Proposition 43, granted that if you add one more force acting equally on all bodies, "celestial bodies can move around the Earth at rest, as in the Tychonic system." In 2013 the Croatian physicist Luka Popov demonstrated in a peer-reviewed paper, using Mach's principle, the kinematical and dynamical equivalence of the neo-Tychonic geocentric system and the heliocentric system taught in academia. In a rotating universe, the centrifugal, Coriolis and Euler forces do what Newton's inertia is asked to do. So the nations teach heliocentrism not because geocentrism failed a test, but because geocentrism implies that this place, and the creature who lives on it, were put here on purpose. That is the one conclusion modern academia exists to avoid.