Youth unemployment in Portugal is 23%. Firms tend to reduce their hirings considerably during slumps. Germany demands more reforms including, presumably, some labour market deregulation. But the Portuguese government now decides to impose a minimum wage and several other contractual constraints on traineeships (e.g., a minimum duration of 12 months).
Traineeships are a form of investment in one's human capital - even if trainees are not paid, they may be better off given the gains in experience, networks, signaling/screening, etc. Why make it more costly for employers to take on trainees? Why risk pricing out many more youngsters from the labour market?