In America, your basic employee is considered to be full-time if they work forty hours week after week, and most employees are dependent upon those hours of service and thereby their pay being consistent from one week to the next. In point of fact, with so many Americans living paycheck to paycheck, there is often a very valid need for many employees to be able to count upon their paycheck consistently being for the same amount and covering the same time periods, paycheck after paycheck. For those fortunate enough to work under these types of conditions, after a relatively short period of time, you learn to bank upon receiving your paycheck for the expected amount which leads to more success in budgeting your funds and your free time as desired.
Over and above the amount of hours, that Americans work each week and receive compensation for, there is often a desire for most employees to have consistent and expected working hours from one week to the next, in which typically the ideal working condition for most employees is to just have a consistent working schedule which doesn't ever change. Again, in situations in which you know how many hours that you are going to work, and you know what times during the workday that you will be working, this will allow employees to schedule and plan out other activities and needs that are required to be accomplished in their day-to-day living of everyday life.
Unfortunately, not everybody can count on either consistent hours, nor can they count on consistent shifts, so that there are many employees that do not know for a certainty how many hours that they will be given to work in a given week, nor do they know for a certainty the actual hours that they will be working in a given week. While, to a certain extent, not knowing these vital things might be OK for those that have no real responsibilities, such as people fresh out of school, with no children, or family obligations, for the vast majority of people, this can be instead a rather annoying burden.
First off, it is impossible to have a reliable budget, if you simply do not know how much money that you are going to make paycheck to paycheck, and as bad as that is, it's even worse for those that have children that are in daycare, or children that have other school activities that necessitate some parent being available, in which, as a parent, you may have to make a choice to sacrifice hours at work, in order to be a responsible parent to your children.
The fact of the matter is that employers in many cases decide on their own as to how many hours you will or will not work, and the actual hours that you will work, without necessarily being interested in your actual preferences, needs, input, or desires. Now, in most cases, a good employer actually does want to coordinate with you, but they often aren't required by law to do so, and unless their actions violate the Fair Labor Standards Act or their own employer manual or something similar, that is just the way it is going to be.
This means that not only do a significant amount of employees work under at-will laws, which essentially mean that they can be terminated at any time, they also work with inconsistent hours and schedules, yet they invariably receive bills and have obligations which have specific set times and amounts that are due. Is it any wonder then that so many of the working class are forever in a state of indebtedness that offers little or no hope of any respite.