A similar example: the tests used to detect the presence of certain chemical substances ("narcotics field tests") are laughably unreliable[0], but police agencies across the USA continue to use them, and courts continue to accept their results as probable cause.
It is not difficult to explain to someone, in under 5 minutes, why IP addresses are insufficient to determine either identity or location, but the state chooses not the understand this information.
That is its nature, and also the reason to be optimistic that it is subject to deprecation in the information age.
0: https://www.washingtonpost.com/news/the-watch/wp/2015/02/26/...