No instance for (Biplate C3 Char) arising from a use of ‘dbg4’

gistfile1.txt

import Data.Data (Data)
import Data.Generics.Uniplate.Operations
import Type.Reflection (Typeable)

-- The haddock for Biplate (http://hackage.haskell.org/package/uniplate-1.6.12/docs/Data-Generics-Uniplate-Operations.html) says this:
--   instance (Data a, Data b, Uniplate b) => Biplate a b
-- But why is there an error on the last line that there is no instance for (Biplate C3 Char)?
dbg1 :: Data a => a -> Bool
dbg1 = const True

dbg2 :: Typeable a => a -> Bool
dbg2 = const True

dbg3 :: Uniplate a => a -> Bool
dbg3 = const True

dbg4 :: Biplate a b => (a, b) -> Bool
dbg4 = const True

type C3 = (Char, Char, Char)

t1, t2, t3, t4 :: Bool
t1 = dbg1 @C3 undefined
t2 = dbg1 @Char undefined
t3 = dbg3 @Char undefined
t4 = dbg4 @C3 @Char undefined