To most developers, interesting problems and technologies are part of the compensation. To attract talent to work for unattractive technology you'll need very attractive salary and benefits. If a developer can't expect to gain transferrable skills from a job, that must be factored in. Jobs where you gain experience nobody else needs are the start of many year-end careers.
OTOH, sexy startups often get away with paying less but, in return, offer environments a DAX-level customer simply can't.
You just described many of the projects at DAX level customers.
I can assure you that I know quite a good set of developers doing consulting for those customers.
The salary and company benefits are more important to them, then using SVN vs GIT, gradle, TDD or whatever everyone in HN talks about.