If I were the owner in this situation, my first thoughts would turn to the manager and I would make every effort to find out what was going on in my store. If it turns out that the manager’s OK, then I would sack the employee, but my instincts and experience point to the manager.
Being late is inconsiderate. I don't care who you are or where you are going. If one is going to be late, one should at very least call.