At 30mph you're plucking your eyebrows and shaving your wossnames.
The time triallists, locked in position and working a hard as they can for so many minutes on a flat road, are the ones who really gain from reducing drag - and they will have tuned their body position and trained their muscles to work with it.
Do tt bikes have a lower bb given they never do corners?
Shorter cranks could facilitate this too!
You wouldn't want to ride one of those bikes for pleasure though.
Think of the Spreadsheets!
And the fully internal hoses saves 4 seconds in the hour, but takes an hour to replace