Take the National Basketball Players Association as an example. They represent NBA players and collectively bargained for a minimum wage, benefits, and processes to address grievances with management. NBA players aren't all paid the same, and they don't have identical terms in their contracts. The union sets the floor.

Yes, but that does not preclude layering individual bargaining on top. The collective bargain could simply be something like "you may not track employees", while still leaving each individual employee to negotiate the compensation they seek. If the workers would rather be completely hands-off they could defer all negotiations to a negotiator, but, again, the workers make up the rules. It's whatever they want.