‘And there came also public servants to be baptised, and they said to him, “Teacher, what must we do?” And he said to them, “Extort no more than that which is appointed you.” '
The tax and custom collectors then came and asked what they should do. These would be looked on by most as unclean and as outcasts, almost worse than Gentiles, but John did not say, ‘Leave your treasonable job' (which many would have said), he told them rather not to use their office to cheat people. They should collect only what was due and take only the agreed amount for themselves that was reasonable. He recognised that in that world tax-collectors were necessary. Better then to have honest ones than dishonest ones. It also demonstrates his lack of emphasis in ritual uncleanness, which makes it even less likely that his baptism was in any way connected with that idea.
His words were very necessary. The chief tax collectors (Luke 19:2) bought the right to collect taxes over a certain area for an agreed sum, and were then entitled to keep whatever they obtained. The tax-collectors then worked for and were responsible to the chief tax-collector. It was commonplace for such tax collectors to seek to extract far more tax than was due, often using the soldiers who went with them to beat and bully people (and worse) into handing over more than was due. Then they would cream off a surplus for themselves and their helpers. They became very rich (Luke 19:2) and very much hated, especially in Palestine which resented any taxes but their own religious ones.