Last Call For Turned Out

I know I said this morning that turnout wasn't the reason why Conway lost because it's an off-year election with low turnout that Dems have won with less. but as Joe Sonka reminds me:

Barack Obama received 679,364 votes in Kentucky in 2012. Jack Conway received 426,964 votes yesterday. #kygov

— Joe Sonka (@joesonka) November 4, 2015

Why do we consider 30% turnout a valid election in any state?

How is that democracy?

Why do we accept this?