Setting velocity makes movement choppy

Why is that doing this to a Rigidbody2D with zero gravity:

void Start()
{
    transform.rigidbody2D.velocity = new Vector3(-10, 0, 0);
}

makes the movement slightly (bet enough to be annoying) choppy in its movement, while this:

void Update()
{
    transform.position += Vector3.left * 10* Time.deltaTime;
}

makes the movement smoother? Or is it just an illusion? I want to do the first version since that seems to be more efficient (setting the velocity once in Start() instead of in every frame), but as mentioned it’s not really an alternative because of the choppiness.

Is it because the velocity is checked in FixedUpdate “under the hood”, instead of in Update maybe?

Setting the “Interpolate” option of the Rigidbody2D to either “Extrapolate” or “Interpolate” made the jitter go away.

My exact problem is described in unitys scripting reference: Rigidbody.interpolation