Perhaps I'm wrong - but there certainly is for Aer Lingus staff:

From a Jan 07 article : "Aer Lingus staff are to receive 10% of revenue collected from new charges for bags checked in at airports. The deal, which will boost salaries for check-in staff, was agreed at the Labour Relations Commission last night. Aer Lingus declined to say how much the new commission system would cost. Under this new deal, the check-in operator will receive commission worth 10% of the revenue collected, i.e. 80c for each bag handled. However, they will not receive commission on lower baggage charges paid by passengers checking in on the Internet. For the first year of the new scheme, each check-in worker is guaranteed a payment of at least €1,000. Check-in staff already receive a 10% commission on all excess baggage charges which they collect"