I'm sure that Jeppesen would love to be able to dictate to the various publication authorities around the world. It would make their own tasks simpler. I deal with them quite a bit and can assure you that they don't dictate to the mob I represent.
Most publication authorities plan to produce 12 amendments per year, on the AIRAC cycle. This results in amendments about every 28 days. As Jeppesen produce amendments every 14 days, one sometimes has to wonder why.
One answer to this is the changes that aviation authorities notify by Class 1 Notam, while a replacement chart is being prepared. Another answer could be that the 14-day cycle allows Jepps to rectify any of their own errors rapidly.
But the chart date problem still exists. I'm wondering if it might be less confusing if the Jepp chart showed the effective date as it appears on the sponsoring chart (ie the chart produced by the relevant publication authority) as well as their own publication cycle date. Knowing a bit about the Jeppesen system, that idea is probably too hard to implement.