Why does it sometimes appear the person who is sharing their location is moving around a lot, sometimes when it’s labeled “live”?

When in Find My it sometimes appears the person who is sharing their location seems to be moving around quite a bit in the same general area even though they are sitting down not moving at all. Why does it look like they’re moving through walls or sometimes stationary in the middle of the road? This happens sometimes when the time stamp says “live”. Is this inconsistent and erratic type of movement a result of satellite retrangulation or something?