It has nothing to do with erosion. The regulations require that run-off from a jobsite does not increase during or after a project. Too much run-off will cause flooding and lower the water table.
During construction, bales of hay and those low fences (as you called them) are used to control run-off. If you are building an office complex with a large parking lot, you will always see a retention basin or two on the property. This is to control run-off AFTER construction is complete.
Basically, if the whole world was paved, a 1" rain storm would cause massive flooding. These measures control that to a degree.
Pain or damage don't end the world. Or despair or effing beatings. The world ends when you're dead. Until then, you got more punishment in store. Stand it like a man... and give some back.