What happens if there are 10 times as many people with cars whose plate ends with a 'T' than those that end with a 'U'
The current UK license plate system, introduced in 2001, has two non-random groups of characters*. If these characters were at the end of the plate (they aren't but they could have been) then you could easily end up with a disproportionate number of cars whose plate ends in the same character.
* The plate starts with a two letter area code followed by a two-digit age identifier, which changes twice a year.
On another note, the article mentions there being 36 possible 'last characters' of a number plate. That may be the case in the USA but in the UK certain letters aren't used on plates (IQ) because they are easily confused with other letters/numbers (10) when being read in a hurry.