The Clipper Card system _must_ fall into this category. I recently called because I was certain my card was being fraudulently used--the value would dip $5-10 f

The Clipper Card system _must_ fall into this category. I recently called because I was certain my card was being fraudulently used--the value would dip $5-10 for a single ride, and there were top-up credit card transactions that didn't correspond even remotely to my credit card statement. Turns out SF Muni and Clipper Card (and possibly Clipper Card's billing vendor?) are two/three completely independent organizations. Everything is passed between them in batches with up to a several-month delay, with batches often arriving out of order. This makes auditing nearly impossible and is what made me think something sketchy was happening. It's a miracle it works at all.