In the recent years I have observed more often some existing limits on the age of a person pursuing an academic career and in the postdoc years spent after the PhD. For example, it is very common to read an academic job opening where the applicant must be under the age of 35 and at maximum must have spent 5 to 7 years of postdoc. It is well known for example that in China (maybe in all country or some part of it) that if you want to apply for an assistant professor position you must be under the age of 35 and not older.
What surprises and annoys me about these age limitations is that they seem to not take into account the academic structure of the country where the applicant got the PhD. For example, I got my PhD in Europe where in my country is valid the Bologna academic system (3+2+3) and I got my PhD regularly in time at the age of 27-28. Even if I wanted to finish my studies earlier, it was not possible to defend my PhD before the age 27-28 because the academic system in my country is structured in such a way that forbids you to end the studies before. On the other hand, there are some countries like the UK, Russia, USA, France etc., where in general the age when you finish your PhD is between 22-25. In these countries, as I was told by some colleagues, the academic system allows the students to finish their PhD regularly in time between the ages of 22-25.
The problem with the situations that I described above is that they tend to create discrimination based on age for someone pursuing an academic career because in some countries you can finish your PhD much earlier than in some others. Supposing for example that someone finishes the PhD at 23 in UK while some other person finishes the PhD at 27 in Italy or Germany, this age gap of 4 years would give an advantage to someone getting the PhD earlier in those cases where exists starting tenure track age limitations. Also the person who finishes the PhD earlier might have an advantage because has more time available to produce scientific output. In addition, it is very common to hear people in academia saying something like: " this person finished the PhD at 23 so he/she must be a genius" without taking into account the academic structure of the country that awarded the PhD.
My questions are:
Have you already noticed in your academic career the situations that I described above?
Does the university/institute where you work takes into account the PhD completion age of the tenure track candidate and the academic structure of the PhD awarding country?
This is an update to my question based on some comments that people have written so far. In my question I considered China as a matter of example where official age limitations exist. I also know some universities in EU that have introduced some age limitations as well for an assistant professor entry. The point of my question is to make people aware that if these age limitations become officially in many countries, then it is obvious that those people who get the PhD earlier have more advantages. The ugly truth is that theses age discriminations happen unofficially during candidate selection by a tenure track committee, where the person who got the PhD earlier is more favoured. I know this information from people that took part in a tenure track selection committee.