It's probably in their interest to have as many vibed codebases out there as possible, that no human would ever want to look at. Incentivising never-look-at-the-code is effectively a workflow lockin.

I always review every single change / file in full and spend around 40% of the time it takes to produce something doing so. I assume it's the same for a lot of people who used to develop code and swapped to mostly code generation (since it's just faster). The spend I time looking at it depends on how much I care about it - something you don't really get writing things manually.