Old school Lutherans, that is. Like Chemnitz and Andrae who wrote Church Orders that mandated fixed liturgical forms, prayers, readings, vestments, times of service, etc. If you refused to follow the Church Order, then you were ousted from your parish. This is how Lutheranism worked at the time of the Reformation and in the generations afterward. This is the kind of authority that is discussed in AC XXVIII and FC X - the latter does not refer to each and every parish minister getting to write his own liturgy, but rather to the various Church Orders in the various territorial churches in the lands which received the Lutheran Reformation. Do all those various Church Orders need to be the same? Of course not. In the Church there have always been different rites - Gallican, Roman, Ukranian, etc. And in Lutheranism, too, there were different Church Orders, different rites. But within each Church Order, everyone was expected and required to keep the Order.
At any rate, we don't do this any more. We live in chaos and without liturgical authority. If you were wondering how Lutherans used to live, see here.