People have varied natural cognitive abilities. A pro can do analysis quickly and make use of it while playing. They have the natural cognitive abilities added with experience and practice and that allowed them to become pro. Someone else can analyze a piece just as much and still forget things while playing because their brain is not capable of storing information as quickly and reliably and handling as much information while performing tasks. No amount of analyzing or practice will get some people to pro level in this aspect. So you cannot judge someone's work ethics or standards just by looking at their results. It's a matter of brain ability as well as good preparation. Understanding can be there, but application still fails.
Not to mention that I've seen many good pianists mark their scores to help them remember certain anomalies while playing. Do they just have low standard and don't understand the piece of music? Or do they just have so much more to handle in their head that some things have to take lower priority...
Valid observations . . . just two thoughts I would add:
1) Pro or amateur music-lover, everyone can analyze music on some level. Some examples . . .
Form: I can notice that a piece is in two sections.
Harmonic: I can notice that though a piece has a key signature of two sharps and begins in D major, it seems to have acquired a bunch of G sharps by the end of the first section. I may or may not also deduce that it has arrived in the dominant, A Major . . . and when that happened.
Rhythmic: there's a repeating figure in this piece that needs to be figured out because it happens twelve times, so I spend a second and take it apart so I don't have to decipher it in "real time."
These things help, I promise, whether we remember everything or not . . . whether or not we know EXACTLY how the first section came to move to the dominant, whether or not we remember every single G-sharp, whether or not we master that pesky rhythm completely the first time around. It's a process!
2) Vis-a-vis pro pianists/musicians marking music, via a flute teacher friend: "If you make a mistake twice, mark it." In other words, don't allow yourself to make a mistake more than twice, once you're aware of it . . . the act of marking the music and the visual left on the score help to guard against that, saving time in the long run that might otherwise be spent trying to get rid of engrained wrong notes. If there's something unusual in the score, it can be helpful to mark it somehow.
On a personal note, I like to write all over my scores about any number of things . . . just part of my process. In the end, if I'm playing from score, I like to play from a clean one, but that's just me, and I certainly know others with performance scores that are heavily annotated.