Management tends* to undervalue software development in general, and see software developers as generally replaceable pieces. So, why bother paying above rate when even paying at rate feels like too much for many companies?
Combine that with the fact that it takes a while for the impact of someone's loss to be truly felt (and the fact that developers who leave are often scape goated), and most managers just can't get their head around the idea that a competent software developer is worth $200K/year + benefits.
Not to mention that turnover costs are mostly hidden costs; rarely will anyone attribute a problem to a single individual leaving, and then connect that fact to "we should do a better job retaining people."
*Yes, there are great places to work where this is not the case. That's just not everywhere, even in SaaS companies.
Combine that with the fact that it takes a while for the impact of someone's loss to be truly felt (and the fact that developers who leave are often scape goated), and most managers just can't get their head around the idea that a competent software developer is worth $200K/year + benefits.
Not to mention that turnover costs are mostly hidden costs; rarely will anyone attribute a problem to a single individual leaving, and then connect that fact to "we should do a better job retaining people."
*Yes, there are great places to work where this is not the case. That's just not everywhere, even in SaaS companies.