Most people whom you see in the J cabin on short-haul AF/KL flights either connect to a long-haul flight or were booked on (discounted) company fares. The remainder consists mostly of people who are reimbursed by their employers (not on company fares) and only rare instances of (luxury) travelers flying on their own dime on O&D short haul routes.

Alas the short haul J market has evolved differently in Europe than in the US. There you normally see ow fares in domestic first class that are unimaginable in Europe: SFO-LAX from $121; ow transcon in Delta One (i.e. lie flat seats) starting at around $800 or ow transcon in domestic first from around $330 - those are prices that I regularly pay as the service and hard product match the price. At current regular prices I would never buy a short haul trip with KL in J.