Trombones hurt my brain

Trombones are non-transposing.  But they are Bb instruments.  But they read in C.  Errrrmmmm....

Let me explain my confusion.  Bb instruments need to transpose their music up a step to be able to match pitch with non-transposing instruments.  For example, the Bb trumpet (or clarinet, or tenor saxophone) produces the absolute pitch of Bb when playing (their) C.  So, for these instruments to sound in the correct pitch, their music is written up by step, so that the sound coming out of the instrument matches the absolute (concert) pitch.  In other words, when these instruments play C the actual note that comes out of the horn is a Bb.  And so on.

Trombones, as I understand it, read bass clef and their music is written in concert (absolute) pitch.  But they are considered Bb instruments.  The mind boggles.


Also, the people who play trombones really should not be referred to as "tromboners."  I think they prefer to be called trombonists or trombone players.