First-class means of the very best standard, or in the best travel class. A first-class degree.
In the post it means the faster service rather than the better one. A first-class carriage costs several times as much for a slightly wider seat.
1adjectivefirst-classOf the very best standard, or in the best travel class.
“He got a first-class degree and never mentioned it again.”
first-class is a quality.