It's a combination of corruption, collusion, widespread inefficiencies that limits high salaries at the margins (meaning that the marginal company available to each employee is never desperate), very high pre-payroll hidden taxation. Also, importantly I think, a lack of competition between multiple globally dominant tech companies with huge profits per employee and a very obvious pathway to monetizing each additional employee's labor.
So, complex answer. But I'd stake money that collusion, often silently government-sanctioned, is significantly more common than in the US.
An example of this is very common in Norway, where practically all education is state-funded and the number of students for each profession is directly decided by the state. Private-sector interest groups have almost direct control over some of these processes, disguised as a public debate in the newspapers leading up to quota decisions. This leads to an almost planned economy of the availability of professionals.
If there was collusion going on, compensation never would have skyrocketed over the past decade.