Encountered over in the !truecomics@midwest.social community:

https://midwest.social/post/18146430

Wiktionary has this to say:

1886, originally for a five-cent US coin (a nickel); use for taxis and buses due to these services originally charging five cents as fare, popularized circa 1915.

The etymology is uncertain; it is believed to originate from Louisiana Creole jetnée, from French jeton (“token, coin-sized metal disc”), though this is disputed. Evidence for the Louisiana Creole French origin include the geographic distribution (Southeastern US, especially Black/African-American), and early spelling as gitney, which is common French spelling for the /ʒi/ pronunciation.

Noun

jitney (plural jitneys)

• A small bus or minibus which typically operates service on a fixed route, sometimes scheduled.
• An unlicensed taxi cab.
• A shared-ride taxi.
• (US, archaic) A small coin, a nickel.
• (in attributive use, US, archaic) Very inexpensive.
• (Canada) An informal lawn bowling, curling, or darts competition in which all players present are randomly drawn into teams.