The Wikipedia page specifically defines a chariot as a horse-drawn vehicle with two spoked wheels. This is also the specific topic of the scholarly work cited to show that "spoke-wheeled and horse-drawn chariots" were first introduced to the Near East in the early second millennium BC. The vehicles on the Standard of Ur do not meet any of these criteria; they are four-wheeled wagons, with solid disk wheels, drawn by donkeys. Further up the page, Wikipedia itself disqualifies these as "more properly called wagons or carts".