Actually, this is false. This used to be the case in the 70s, but after the Wassenaar Agreement[1], this was removed from nearly all collective bargaining agreements[2]. Some have salary grades that increase automatically by year of experience, but this isn’t the same, because it won’t increase the wages for people starting their career. In general, the stronger unions are able to negotiate salary raises above inflation[3], but this of course depends on the percentage of employees that actually join a union.

[1] https://en.wikipedia.org/wiki/Wassenaar_Agreement [2] https://www.volkskrant.nl/nieuws-achtergrond/koopkrachtrepar... [3] I recently verified it for my own collective bargaining agreement, and on average, the raises were about 1% point higher than the inflation

But regardless, the wages still keep slipping against inflation.