What are parents/guardians required to have in order to homeschool or unschool their children?

If they don’t need a teaching degree why not? And who can’t be a homeshooler parent or unschooling parent? What do the homeschooled and unschooled children miss out on? I can see basic arithmetic can be learned without going to school but aren’t there things a home can’t provide? What are the pros and cons of homeschooling and unschooling vs sending children to school?