Luke says they feared the people, because the people at that moment were for Christ. He was their great prophet, their healer.
There are many, many examples in Scripture of how prophecy is wonderfully fulfilled. Often it happens against all the odds, and insuperable obstacles seem to stand in the way. How will this problem be dealt with and how will that? God gives the answer as events unfold and we learn to put our trust in his word more than in the common-sense predictions of man. Joseph’s life history is a series of such unexpected happenings, and we praise God for his foreknowledge, his skill and his power. God’s word prevails, and we may apply this to the promises of God also. We have a promise from the Lord and we cannot see how it can be fulfilled, but we continue to trust the Lord as Abraham did, and eventually, in God’s time, the promise is fulfilled.