I'm beginning to think this is completely different Universe,even before the Narada showed up. There are too many inconsistencies in technology for this just to be a different branch of the timeline from when the Narada shows up.
Which is fair enough considering Into Darkness
. But I'm happy with the explanation offered by the writers.
Well remember, they only wrote what Spock was trying to explain the events of ST09. But if you want to buy 20yrs is enough time for them to create warp drive capable of going from Earth to Vulcan in 30 minutes, fine by me. At the end of ST:TMP, Scotty said it would take the refitted Enterprise 3 days to reach Vulcan.