Many companies today have drug and alcohol rehabilitation programs. In today's work world, unless you're in a management position, it's common for employers to hold off giving employees benefits until they have worked with them for a certain period of time. This can be after the first 90 days. Often it isn't until after 6 months. Some employers limit benefits to only those people working full-time.
Many employers only hire people to work part-time.
And these part-time employees will not receive benefits, no matter how long they work with the same employer. But anyone can understand why business is done this way. Let's say you're an employer and you hire a new employee and give them benefits right away. Now you need to spend another good deal of time, energy and money to undo these benefits. And - most benefits cover employees for at least 30 days after they've left their position, so add this to what it's already cost you.