There are many people who may also be involved in an accident and they may also need a break. This is why the company may grant them leave. In such cases, other employees may be handling the job. In many cases, the company may also allow them to work from home as well.
Yeah, that's very correct. Whenever you're incapacitated to work, you will given time to heal. All you just have to do would be to pray and hope that your company doesn't replace you at work when you don't come back sooner. It's why some people prefer working on jobs that offers security for their job. Having an accident while working for the company will never have them replaced unless they cannot work again.