Firstly, the Germans were in the war for longer than anyone else. They really started in 1937 in Spain with the Condor legion, going on to 1945 (8 years) whereas the Brits only did six and the americans only four, effectively. Basically, the germans were fighting longer and therefore had more time to notch up scores.
Secondly, as the war turned against Germany, it became increasingly difficult for allie pilots to even find german planes to shoot down! Contrariwise, the few german planes flying had no problems in finding enormous numbers of allied aircraft. Quite simply, the germans just fought more air battles.
Thirdly, its very important for intelligence to know how many enemy aircraft have been destroyed but very difficult to confirm kills through all the confusion and the false claims and the multiple claims. The Brits were probably the strictest in confirming kills before assigning them to an individual pilot, requiring the greatest level of confidence that the enemy aircraft had actually been shot down. Conversely the Germans were undoubtedly the slackest at this, assigning even marginal possibles as definite kills.
Fourthly, the luftwaffe very much had an "Ace" culture. German Aces (experten) were cosseted and feted. Other members of the squadron were expected to follow the lead of the experten and basically help them build up big scores, while taking all the chances and providing better targets for enemy aircraft (basically dying more). In contrast the RAF (and the USAF too for that matter) operated much more on a teamwork basis.
Fifthly fighters dont just gain air superiority. They also have other duties - escorting bombers, ground strafing, and so on. Luftwaffe pilots, with all the emphasis on "big scoring" tended to consider this kind of stuff as "beneath them" and either ignored it or skimped on it. Conversely allied fighter pilots were expected to do close support and ground attack if required and that was that!
I had considered that, but that is what appears odd to me: I would have thought the Brits, since they were fighting longer, would have had a larger number of high-scoring aces as compared to the Americans, but that doesn't really appear to be the case.
"as the war turned against Germany, it became increasingly difficult for allie pilots to even find german planes to shoot down!"
This also should have contributed to more Brit aces, since they initially had the Germans "all to themselves." As the war progressed more and more American pilots were looking for fewer and fewer german planes.
"Conversely the Germans were undoubtedly the slackest at this, assigning even marginal possibles as definite kills."
I recently read a book from the German point of view "Jagdgeschwader 26" was the title, I believe. In many cases the author was able to compare Allie claims and German claims for the same battle. The author made it sound as if the allies were constantly claiming twice the number of victories as they actually achieved. I guess gun cameras aren't always definitive.
With my original question I was really asking if the RAF operations/tactics were significantly different from the Americans and could those differences account for the apparent disparity in the number of high-scoring aces? Or did different assigned responsibilities offer the Americans more opportunities? Thank you for your answer; you pointed out several things that I did not know.