sql server - Clarification on SQL PIVOT -

can tell me missing in second pivot example. returns null http://sqlfiddle.com/#!3/2b405/2

this literal answer:

there no car, truck or bicycle in vehicle_parameters table. nothing missing in statement, result of null correct.

here other samples of pivot may want up: https://technet.microsoft.com/en-us/library/ms177410%28v=sql.105%29.aspx think explain dealing nulls well.