That seems pretty fast for Google. We mentioned above that they didn't have the Path subway in Manhattan and New Jersey either - and they seem to have added that too recently - that only took 111 years!
Still missing is the London Overland lines that TFL added in May 2015 - so that's 4 years now. And the 2015 TFL Rail line (to be renamed Elizabeth Line when the Crossrail tunnels finally open). And many other systems such as the 120-year old Glasgow Subway, the Ottawa Trillium Line that opened in 2001,
The oddest inconsistency I've seen is that they've had the DLR in London for years, but haven't yet added in the Canning Town to Stratford International branch that opened in 2011! Though it's always seemed odd that Seoul is their only as a graphics layer, rather than the vector-based stuff most cities have - and also seems years out-of-date.