Even when a motor is star connected, the neutral of the motor does not get connected to the neutral of the supply.
Common three phase supply voltages in the US are 208V, 240V and 480V, so there you don't find a common situation where you will want to switch a motor between star and delta.
Instead you see motors where there is a factor of two voltage difference between the different possible motor connections, eg 240V or 480V.
