Plotholes, bad writing, bad acting.

First off, to get that out of the way, I'am old enough to have seen a lot of the so called "classics" in the movie theater.

I saw this flic about 30 years ago for the first time, and then, I thought it was good. Interesting how filming, writing and acting have changed since then.

Take Le cercle rouge: there is very little story in the first place. That's fine, somtimes. Here it is not. By the end, we know practically nothing about the lead character, except that he is a criminal and there was a girl at some point in his life. What we do learn however, is that in the 70's, in France, you could seemingly shoot dead unarmed people, in the back, as long as they are running. (well, I lived there, you could not.) Also: every shot kills instantly, well, unless there is one important sentence to say, but then: dead.
We learn that when a security guard is being attacked and held by the attacker, they do not make any sound, never mind screaming, but instead wait silently and without any movement what so ever, until the second attacker arrives a good 5 seconds later and knocks them out.
We learn as well, that people permanently appearing in places they could not have known of. Most notably, I the last scene, Vogel appears out of nowhere in the staging house, just in the right moment. The huge property is -as we see seconds later- crawling with police, which are undoubtedly watching the house, but yet he get's in unnoticed. Never mind how he got there in the first place and even more: how did he know WHERE to go.
Also, seemingly, when you are a police officer and your prisoner jumps out of a moving train and then very slowly haules himself (injured?) away from you, you do not run. No. You walk casually behind him, shoot all your ammo in his direction (never mind he is an unarmed man, about whom you tell your superior later that you think he might be innocent) and then decide (although you can still see him) he is not worth breaking in sweat. No let's rather send 100 police officer on a pointless goose chase hours later. They btw., have never seen a creek before and are really stunned by the experience. And have seemingly no way to get the tracking dogs across that little stream and continue the search...
And don't get me started on the alarm system in the jewelry store.
Ok: they have 64 (in words sixty four!) glass breakage detectors on a small restroom window, but nothing to detect if the window is being opened? Right.

Ok, I mean Montand, Delon, Bourvil, great actors. But the writing in this movie is so bad...
but, what really stunned me was that all this did not bother me 30 years ago. Why is that?