What is preventing Zeiss from paying higher salaries to mirror grinders, so that young people consider that career over alternatives?
The answer is that some people do quit and retire early, but even more are attracted to that career like moths to a flame, and work until they can't.
I do think they should raise pay for their existing employees at the same time. In fact, they should tie the compensation to progression in skill and experience, so that people who just came for the money and aren't cut out for the work or aren't in it for the long haul aren't attracted to the job. That's basically the traditional model anyway.
And yeah paying employees well might cost a bit of money (but really, not that much in the scope of things). If talent is their production bottleneck, it will be well worth the expense.
Software industry has always been plagued by attrition. Some companies pay well and mostly employ younger people. Older employees eventually filter out, either because they have already earned enough and prefer better work-life balance, or due to ageism. And then there are occasional downturns, where many people lose their jobs, can't find new ones, and end up leaving the industry permanently.
People generally prefer careers with multiple viable employers. Not just in the world, but also in the same metro area. That way you are less likely to get stuck in a job you don't like. But if you are an employer with unique requirements. Of skills that take years to learn and that people are not likely to acquire on their own. Then you may need to pay ridiculous money (more like AI than FAANG) to substantially widen your talent pipeline. And if you pay ridiculous money, you risk ridiculous consequences.
And if they do not, they risk ridiculous consequences. If Zeiss cannot afford to pay more, then it is underpricing its products.
Also, it sounds like the entire premise is "people don't want to work because they're not being paid enough" which is enough of a good reason by itself.