I've seen gen 3 22s go for tens of thousands of rounds. Our city guys have been using the same ones for years. County carried 45s then this year went to 9mm. It's not like they are any more fragile than berettas locking blocks or sigs alloy frames. The gen 4 and gen 5 may well be better, I don't doubt that at all. But the glock 22s are cheaper because of the trade ins from departments going to 9mm. Not because they are particularly fragile. There was issues with g22s running lights not cycling with worn recoil springs. Notice the one pictured has a light and has ran fine. My carry glock 27 doesn't have a light (nor rail)
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That was just one day of shooting. All 40s. (Except the G20 and it was shooting 40 as well) The glock is my favorite and has many thousand rounds through it. Other than springs its had no issue. The 226 has a slight accuracy edge but I can shoot the glock as well as the 96, or USP. All are great guns. I'd be shocked if either failed before 50k rounds other than maybe a spare locking block. At 150 per 1k rounds that's 8 thousand dollars in ammo.
For pure longevity though. I believe the dual recoil system and big fat slide of the USP would last the longest. It's my least favorite of the lot.