That's not the issue. Union Square on the Park Avenue line and the old South Ferry on the 7th Avenue line both had platform "gap fillers" installed decades ago that require the train to stop at an exact location each and every time:

https://www.atlasobscura.com/places/14th-street-union-square...

Every station has lining boards that the conductor must check before opening the doors to ensure that the entire train is stopped along the platform:

https://www.topic.com/conduct-yourself