Publicani were really hated. Roman Empire had a tax farming system where private individuals paid the taxes in certain area out of their own pocket and then tried to make a profit by collecting the taxes from that area to themselves. Made it so that the state didn’t have to concern itself with the actual collection and got a guaranteed sum. But it also made it so that it was beneficial to the publicani to try and squeeze as much taxes out of the people to either not have loss or to have maximum profit. Though the term publican covers more than just tax collectors.

Apostle Matthew was a publican.