Why do Michigan city income tax returns have the incorrect due date at the top of the first page for the last two years? They still show due date of April 30, 2019... S/B and easy fix - why isn't it caught after two years?

[rodneylee]

The first page of Michigan city income tax returns (Battle Creek, Springfield and Grand Rapids, at least) reflect an incorrect due date and has for the last two years.  It still shows a due date of April 30, 2019 (which was the due date for the 2018 returns).  Should be an easy fix - can't believe nobody has caught it in two years.