I've never worked somewhere where the proper channels meant "coordinate with finance", but "file a bug/feature request to track this work and time time spent on it" should be standard. If it's not worth 5 minutes for the requester to do that, it's not worth however long it would take me.
This makes it easier to query and show what you've done in a time period. It makes it easier to go through the list of your assigned tasks and understand where it fits in the priority order.
Sure, but the HN crowd cuts much wider than just people working on mobile business apps.