You must assume that your employees will miss work before you start hiring because it happens. But, if you (and they) plan for it, business will continue as normal.
We are hiring people, not machines, and people have commitments above and beyond their jobs. Some have elder family members or children or even a spouse to care for, and that can mean they need time off or to be able to work from home. How you plan for this is important.
It would be nice if the person you are interviewing told you up front that they have responsibilities at home - but they usually don’t. And things change, so lack of responsibilities now doesn’t mean they won’t appear later. The lesson from this is: assume from the beginning that there will be times they need to be off.
The first thing you should do is sit down with the person who may need to take time away from the office/plant/warehouse and discuss how their job can be done if they are not physically there. Obviously, your fork lift driver can’t work from home, but do you have a back-up certified operator that they can train? Can your payroll clerk come in after regular hours? Can you add a phone line to your warehouse supervisor’s home that they can use to take care of business? Or can you change the hours they work to fit their need? If working from home or changing the hours are not viable options - look at how the work can be portioned out so that others take up the slack. This is the last resort of course, because you are adding to the work load of others- so you want to be sure that you do this fairly and that the appropriate training takes place. Both you and the employee who needs to be out should be sure to express your appreciation for the help.
The majority of employees who find themselves needing to take time away from work want to keep earning a salary and they want the work to get done, so they may have solutions that you won’t think of - which is why it is most important for you to sit down with them and make a good faith effort to work out an accommodation.
FLSA and ADA require that good faith effort is made, so going into solving the problem in partnership with the employee is your best bet for a win-win outcome.
When your employee comes to you regarding time away document the conversation. Just a note in your daily planner is usually enough to start with, but if things get sticky, full minutes of the meeting and maybe another person in the room with you will become necessary. Remember that you want to reach consensus with the employee if at all possible. Working with the employee who needs time off is the right thing to do, but be sure to keep the well-being of your company in mind!