The equivalence is between uniform acceleration and a uniform gravitational field. Breaking the uniformity, which the universe does for us whether we like it

The equivalence is between uniform acceleration and a uniform gravitational field. Breaking the uniformity, which the universe does for us whether we like it or not, has consequences. Real gravitational sources aren't uniform (they tend towards spherical) and come equipped with a tidal field with a potential and gradient. This is intrinsically gravitational, not accelerational. The non-uniform distribution of matter (including radiation) in the universe also matters. You can rest an accelerometer on the surface of the Earth and it will report ~ 1 g (upwards) for many -- even billions of -- years, with no ill effect. How long can you accelerate a rocket containing an identical accelerometer? Consider fuel, and crashing into matter (up to distant starlight and the cosmic microwave radiation) after a few months (of ship time) of the accelerometer indicating ~ 1 g (forwards). You don't get strong twin-paradox effects involving the Moon-walking astronauts, or long-mission robot probes on the Moon or Mars, even though the local equivalent of "g" is considerably lower than that here on Earth. By comparison, if you and and two roughly identical astronauts were to undergo hundreds of days (or Martian sols, or a few lunar days) ship's time in spacecraft doing a round-trip under constant accelerations of ~ 1g, 0.6g, and 0.17g respectively, the lesser-accelerated "twins" would be visibly older than you at the end of your respective round-trip journeys.