A restaurant in the Rehavia neighborhood of Jerusalem, Heimishe Esin ( ‘היימישע עסין’ ), was told that it could not hire waitresses on Thursday night if it wanted a Badatz kashrut certificate. So he removed women from those shifts. Thursday is one of the busiest nights so it also means that women are excluded from a night where table tabs are high, customers frequent, and significant tips accumulate in the kitty.
Rehavia is a mixed religious neighborhood in the center of Jerusalem. It includes secular and religious Jews from many different streams of Judaism. The restaurant which serves classic Ashkenai home style meals attracts a lot of students from a nearby yeshiva but it also serves local secular and non-Haredi residents and has a large secular high school across the street.
A Badatz certificate increases the marketability of a restaurants food, especially in neighborhoods near Haredi insitutitions. The extra economic edge means that Bedatz can use economic incentives to encourage practices that are prejudicial against women employees.
Correction: The picture originally with this post incorrectly showed Badatz Edat Haredit. The kashrut organization responsible is Badatz Agudat Israel. The picture has been corrected. Thank-you to commenter Daniel below for noting the oversight.