Why piramids around the world have square bases and not triangular?

It's common knowledge ther piramids are built in that shape because the triangle is structurally the most resistent shape in geometry

But wouldn't that make it intuitive to also give them a triangular base instead of a square one?

The square base is understandable when it comes to normal buildings because of interior space efficiency, but the piramids don't seem to have an actual reason to require it