Why isn’t the new pope elected by casting lots? In the Gospel they even elected an apostle by casting lots!

Answer: The election of Matthew to replace Judas by casting lots (see Acts 1:16-25) concerns an ancient Hebrew tradition (see 1 Sam 14:41; Lk 1:9). Already in the early Christian community this procedure was replaced by a less visible process (see Acts 6:3-6; 13:2-3). The Church as the community of believers in Jesus Christ, as the son of God, knows that they are animated and led by the Holy Spirit. Their lives are shaped by the power of the Holy Spirit and they are no longer bond to the letter of former rules or the details of former institutional values. The Christian community, in other words the Church, can modify or develop these in the light of new historical and social situations through the power of the Holy Spirit that is given to them.