We can see it, it's obvious that the system in France(and other EU countries) works this way, it's just not really relevant when talking about salary. When I sign an employment contract for 100k euro that's my income. The fact that the employer then has to pay another 40k or 100k or a 1M euro on top of it to keep me employed is not really relevant because it's not my salary - it's their cost to keep me employed. The main proof being in two things

1) like I asked you in another comment - if that contribution was removed, I'm sure you wouldn't feel like you got a paycut.

2) if that did happen, your employer wouldn't magically decide to give that money to you instead, right? It is not and never was your income.