Marx wrote:I think they were tax collectors. Back then tax collectors weren’t as loved as they are nowadays. Most worked on commission & their percentage take was whatever they got above what Rome asked for.
Tax collectors were definitely unloved in Roman times - they had a reputation as sinners and cheats. The story of Zaccheus "a chief tax collector and was wealthy" (and short) is recorded in Luke chapter 19. In the story, Zaccheus acknowledges Jesus as Lord, and gives away half his possessions to the poor, and repays four-fold any taxes he has cheated anybody of.
The money changers were in the temple forecourt - "regular" money was deemed not acceptable as a worthy offering, and had to be exchanged for "temple money". At a premium. In Matthew's story (chapter 21), the tables of the money changers were overturned and Jesus drove the money changers out of the temple.