Oh. Garbage bags...Yeah they're usually black here in the USA too.
I don't know why I was fixating on grocery bags...which aren't black...

And most taxi cabs were yellow in the USA...I never heard of black taxi cabs...

well maybe jitneys

[and inside joke since in Pittsburgh and maybe other cities 'jitneys' are what you call privately owned cars which serve the same purpose as {taxi} cabs but are illegal...Since alot of cabs won't come to Black neighborhoods, people call 'jitneys'... the passenger sits in the front seat and pays the driver for taking him or her to their destination].