1) the speed at which AI-generated codebases grow is far in excess of what human developers can achieve. What took years to accumulate in the past can be produced in a few days/weeks.
2) past large codebases that end up in a similar state would often see a mixture of developer talent. So while you might have a few developers who produce dross, there will also be a few who can pull it back together. You start to see threads of sanity appear, and from that the potential to refactor further, rather than the uniform spaghetti monster that's near unassailable from every direction that we're now getting from the pure-AI projects.
3) external perception differs. AI has been pitched, sadly by sales, influencers and shills rather than experts in the field, to business leaders as the solution to all development problems. When you present this issue to stakeholders you're then immediately put on the defensive, e.g. it's initially viewed as negativity for the sake of negativity. With past technical debt discussions, outside of a few key parties (too often the person responsible for overseeing said debt developing), I've found that it's relatively straight forward to explain technical debt, the need to refactor and maintain systems as a going concern. For the technically disinclined it's easy to draw parallels with building maintenance: you don't expect to build an office and then never spend another cent, it takes continued investment and maintenance to keep it safe, clean, functional and compliant. The difficulty again with the AI projects here I think comes back to the accelerated timeline, as you're inevitably going to be saying months after it's created that it probably needs to be burnt to the ground in lieu of the far greater task of refactoring it. As opposed to a legacy project that has been going for years or decades, where it's a far more palatable concept to take drastic action.