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50% of my dynamo bikes have a USB charger fitted and I have one sitting for the other bike but I'm lazy. I'm hardly a 'normal' rider though and you can charge during the day if you forgot your cache battery. The point is, dynamo lights for normal users means you can just leave the lights on MOST of the time so funky switches are a waste of cables and increase failure modes.
Next.
Yeah, because that happens a lot.
"More visible, more of the time." is still not "all of the time" if you want to be pedantic with edge cases.