For 90% of rock, country, folk, blues, etc. just knowing the major and minor scales and the major and minor pentatonic scales gives you all you need to start picking up bass parts by ear. Since the pentatonics just leave out two notes (for 5 notes in the scale rather than 7…the 4th and 7th are left out) it’s not very hard to learn those four scales. The only other thing is understanding about the use of chromatic passing tones (the notes NOT in the given scale).
I’m sure someone will come in here talking about the modes, mixolydian (a major mode) and dorian (a minor mode) have been all I’ve ever needed to use because I do not play jazz, prog rock, classical or non-western music built on modes.
Reading standard notation is important because when you're learning on your own from books, that’s what you find in books teaching music, not tab. Music is music regardless of what instrument you play. Bass tab isn't going to help you learn songs on the saxophone