The probate system serves as a fertile income source for those that serve in its ranks. The fees they receive from probate may constitute a substantial portion of their practice. When one of the owners of jointly owned property dies, the ownership is automatically transferred to the survivor. But at the death of the second owner, the property must, naturally, be probated. So probate isn't avoided, just postponed.
Joint ownership has some risks, too.
As a joint owner, you are not in complete control, since both owners must agree to sell or mortgage the property. Holding property in joint ownership with children can allow their legal obligations to devastate your assets. Unless other arrangements are made in advance, only the probate court, through its agent, may sign for you. Your family may be forced into probate court to obtain permission to care for you and your affairs. My estate is really too small for me to worry about probate.