Why do Americans drive on parkways and park on driveways?
'Parkways' because of the extensive landscaping on the right-of-way. Long, skinny 'parks' with a road up the middle.
'Driveways' I'm not sure about, but affluent homes on extensive grounds had 'drives' leading up to them which, probably by the magic of advertising, became 'driveways' when attached to more modest houses.