When trying to join a ride, it took me a second to figure out that i needed to leave the "needs a ride" ride in order to join an actual ride.
While treating "needs a ride" as it's own "ride" works, i think a better solution might be to have people mark themselves as wanting to attend/attending the event and then anyone who is attending and hasnt added themselves to a ride yet gets automatically sorted into a "needs a ride" list until they join a ride.