The gap moved from producing to checking
So where did the senior-junior gap go? Into checking. Security research suggests that somewhere around 30% to 40% of AI-generated code snippets contain at least one known class of vulnerability. One study of 304,000 AI-written commits across 6,200 projects found AI-introduced security problems had a 41% survival rate, meaning many were never caught. Meanwhile, one analysis of 211 million lines of code found the average developer pushed 75% more code in 2025 than in 2020.
Put those together: 75% more code, but nobody hired 75% more reviewers. The bottleneck was never typing. It was always knowing whether what was typed is correct, and that part is untouched. That is your gap. Not speed. Judgement.
This is not just coding. McKinsey found around 46% time savings on routine tasks and under 10% on complex work. AI eats the routine. The complex part barely moved, and the complex part is where the money is, in every job.