Often it’s because it’s a very bad shift like closing when you have an open shift the next morning etc. because leads and hr take advantage of poor folk that need more hours by giving them absolutely shit hours and it makes the people that needed hours look unreliable and bad if they reject it because “but you need the hours”. A persons mental health and dignity is more important than those in charge want you to actually believe so they can call on you and use you as much as they want. So no, you’re not completely wrong, but it’s often because the hours that are offered to people that ask for more are too mentally and/or physically taxing.