It's about trusting your ear - if you can't determine relative pitch...
I agree and since learning the violin I began to understand to appreciate this very skill; as well as the benefits of playing fretless, allowing the player to change the intonation on the fly. Sorry, I realize my earlier post about "no excuse for fretless players

" must have sounded rude to you. I should have emphasized more that it
is a key skill of a fretless player that he has to master intonation; which includes being able to determine pitch as acurately as can; a skill of which also fretted bass players surely benefit, without question.
If your ear is taught how to hear pitch and to recognize the notes to adjust tuning your bass, there is no reason that a tuner is necessary except because people choose to use one. Musicians tuned their instruments by ear because they were taught how to. No one needed a tuner to do it.
It is a device of the times! To me, it is in use and represents the lowered musical skills that musicians tolerate. People don't aim high in music. They aim low and sometimes make excuses for this. I feel that they should stop this.
Not being able to use your own bass means that that musicians are less skilled to perform the most basic task of music, to tune your own instrument. It might be true that players today aren't skilled enough to use their ear, maybe the most fundamental skill necessary to be a musician.
I agree with you, you are right. People should aim high in order to fully enjoy playing.
But was that the point? I agreed that it is desireable to learn to tune by ear - as well as to train hearing and determining pitch.
My point was:
Why not asking the student who uses a tuner,
why he does - before telling him to quit or making fun of him?
Maybe he has trouble doing that in front of others because he is nervous or shy, or whatever reason.
This is not aimed at you nor at SteveCS or anyone else in this thread - I got aggrevated when this topic came up here, too; because I had read enough high and mighty sounding statements about that topic, here at TB, while I did have problems myself in tuning by ear in front of other people, as explained earlier. To you, @SteveCS and all others: I am sorry, in case my tone was rude, or got too much into off-topic.
Now, since this thread is called "What Is Taught Without Only Teaching the Facts!" - to me teaching:
"If you can't tune by ear, you should quit" or even worse the subliminal message one might get:
"If you can't tune by ear, yet, we are gonna make fun of you!"
...is not only teaching without teaching facts, it is wrong. Yet, this attitude seems to exist; hopefully not in schools/academies, but systematically within the community of players, of which some also do teach.
That is the point I try to make in the range of this thread.