the agent is presumably receiving a payment for their gig-booking services!

An interesting question. Most of the agents I've dealt with get their fee from a percentage of the gig money - usually 20% and 25-30% for really big paydays. If they didn't get us gigs, they didn't get paid, and we certainly didn't sign any contracts offering cash for services. The only contracts we ever signed were individual ones - one gig at a time - 5 gigs, 5 contracts, 5 percentage rake-offs.

Either the agent in the case quoted is desperate to get the band some recognition with a view to future cash coming in at a later date, or they're paying him for the promotion. I hope for their sake it's not the latter.