Just not (mostly) the British government (though the UK government also regularly has to step in to take over for failing operating companies...)
E.g. the Dutch, German, Italian, French, Quebec (via Keolis; a joint venture between French owned SNCF and a Quebec pension fund), Hong Kong governments all have significant ownership in UK rail franchises. Only a handful of franchises are run by purely privately owned operating companies.
Also, these are only the train operating companies, the rail and infrastructure itself is owned by Network Rail, which is state owned (and by the UK, not France!)
It's not like the French TGV/Thalys or the German ICE would run HS right into and out of the cities either.
Maybe in China and Japan, but hey, they are different.
(Am Brit)
Previous world powers came to pre-eminence when less of the world was known and later world powers are nuclear and haven't really directly invaded, fought or attacked like the British did.
This map brings it home more than most https://i.redd.it/75nqzhfp42r21.png and it only covers a single instance for many of those countries, the British (English first, rest of UK later) and the French spent most of a millennia beating each other up when they had no one else to fight - I mean Churchill gave orders to shoot French military if necessary months before the end of WW2 (between VE and VJ day) during the Levant Crisis.
https://www.railway-technology.com/features/feature-top-ten-...
Let's see how the Japanese do with their https://en.wikipedia.org/wiki/SCMaglev on the https://en.wikipedia.org/wiki/Ch%C5%AB%C5%8D_Shinkansen in a few years.
(In the Shanghai case it's practically laughable, because it's such a short journey the top speed is practically irrelevant: it spends half its time accelerating/braking)