The Moon rules fame, amongst other things - and since most people find their fame through work, that's the logical extension. I use the Anchor myself, but I do get it.
This is how it came to be: In astrology, the Moon rules the public, and its ever-changing moods. Since the favour of the public is what makes you famous, it falls under the Lenormand Moon card, and by extension, in some countries - that's also your work card.
The Moon rules other things, too, that's just an interesting connection.