Since the military took power and shut down all the unions, except the state backed yellow ones which were member of Turk-Is Conferation, in 1980 it is almost impossible to get official recognition for signing a collective agreement in large multinationals for progressive or left unions in Turkey.
According to the Turkish legislation, which had largely kept those articles created by the military junta until today, only one union can represent workers in one workplace. In order to get such recognition unions have to organise more than %10 of workers sector wide (national level). They also have to organise more than %50 of the workers in the given workplace to be able to represent that workers.
This context has been protecting the large multinationals active in Turkey against the progressive unions. State backed yellow union were preferred by those corporations like BOSCH and implanted in factories by the employers themselves. To engage with the massive task of taking over these factories, against the will of such unholy alliance is meant taking very high personal and organisational risks.