Tangential, but I wish there was open traffic data with high coverage for planning low-traffic cycling routes. Looked at openly available aerial images, but the resolution is not high enough to detect traffic

I would think it would be a challenge to get useful data from such a source even if resolution were high enough. That nice low traffic road may have been photographed in the weekend, outside traffic hours, on a national holiday, because of a road black a kilometer away, etc.