Because of things like Coriolis effect and convective currents, there just aren’t winds that blow across the equator, not at the scale that would blow a hurricane from one hemisphere to the other anyway.
Winds tend to blow along and away from the equator, not across it.
The earth spins faster at the equator, which is the reason for the rotation of hurricanes. They spin counter clockwise north of the equator and clockwise south of it.
Edit: The reason they don't cross is not because of the Coriolis effect working against the original rotation direction if a hurricane crosses the equator, but rather because the storms are moving away from the equator