I have seen the term used when calling out for a taxi, but I thought it was a term meaning boss.
Honcho in English is an "英製和語" term derived from 班長【はんちょう】. In Japanese 班長【はんちょう】 refers to the head of a small group/team, and it's not really a big word. 班【はん】 means a team/group/squad of typically 3–10 people. Practically, you will never see romanized 班長 in Japan, and the normal romanized spelling of 班長 is hancho, not honcho.
If you saw Honcho on a signboard in Japan, it's probably 本町【ほんちょう】. It's just another place name which literally means "main town". There are hundreds of districts called 本町 all over Japan.