The automotive industry used to be almost almost purely driven by the standard QS-9000.
It has now been replaced with a multitude of standards. ISO 9001 and TS16949 being the primary ones.
TS16949 registration has been promoted heavily as the standard for the automotive industry. However, that does not apply to all companies. The key for many suppliers is the ISO foundation, not the TS specific requirements. Depending on their Tier level, a company could be ISO registered with a TS compliance (as long as FMEA requirements are met).
Consequently, many of these suppliers request from their clients or OEM’s that they be accepted for their ISO registration. They are usually accepted.
There are many instances now, where companies add to their ISO system in terms of environmental (ISO 14001), and health & safety (ISO 45001).
They will add these two standards in a certification manner as opposed to registration. It is less costly, and more time efficient.