At one point, African countries were used a damp for scrap metals in form of cars. I remember early 90'z there was an influx of Japanese vehicle importers in a East African countries. These cars were dirty cheap and pure crappies where 6 month driving was eternal. This resulted in an influx of under Mango tree garages and insane traffic jams.
Hence the creation of old age limits, for US and Canada, Dan_hunter nailed it.