You can manage things in your life when they occur instead of spending money to displace them or risk losing your job because of them.

In another way, if you present a worker with the option between two jobs with the same hourly rate, one having flexible working hours and the other not, which would expect to be more likely choice? You can then measure the value of this choice by changing the hourly rates between the two until you see changes in outcome and you would be able to estimate exactly how much "more money" it appears to be "worth."