“What does being a tax collector have to do with Matthew’s greater accuracy in the recording of Christ’s words?”
Matthew, alias Levi, was a tax collector. In the Roman government, that was an office you bid for. The Romans would tell the tax collector how much they expected in taxes, and anything collected above that was the tax collector’s pay. As you might guess, this made the tax collector very unpopular.
Do recall that this was a time when there was no carbon paper, no photocopier, not even a typewriter. Everything that had to be recorded had to be done by hand on clay, wax, or papyrus. To be in some offices, shorthand was a required job skill. These people were called “ready writers.” Psalm 45:1 uses the term. In the Greek, that term would be “oxygraphos” or “tachygraphos.” “Graph” refers to written recording. “Tachy” is the same term that appears in our words “tachometer” and “tachycardia.” Oxygraphos is a synonym.
So, Matthew’s Gospel has really detailed accounts of Jesus’ words because Matthew could take shorthand. There’s a really good chance that he wrote what Jesus said verbatim.
Source: Missler, Chuck. The Book of Matthew: A Commentary. Koinonia House.