In many (crowded) places in Indonesia you will see parking officers (called tukang parkir) 'helping' you park your car or motorbike. Especially for motorbikes this is almost always unnecessary. Sometimes it's clear they are employed by the place you are parking at (like a parking area for a restaurant) but other times it's not so clear and other times I'm pretty sure they just show up and try to get money while unaffiliated with the parking spot. I am curious about their legal status. Are you required to pay them or do they just make it appear like that? Is this more like a common courtesy for poor people to have some kind of job? Should you ask the employees of the place you're visiting about the parking? What if it is just 'on the street' servicing a bunch of places?
This article would suggest there is a lot of corruption behind it: http://www.reinventingparking.org/2012/05/gangsters-in-indonesian-parking.html