While I still believe this, the question has led me to think further. What should an employee have a right to expect? Workplace rights are typically defined by law. Some employers (the smart ones, anyway) go beyond legal requirements and provide more flexibility than others.
Some maintain that an employee's needs are completely individual. I hear this in the "if you don't like it, then you can just leave" attitude. It also shows up in the choice rhetoric. Women choose to drop out of the workforce, and they choose careers around their family. So they shouldn't blame their employers.
It makes good business sense to offer flexibility to your employees. It's good for productivity, innnovation, and recruitment. It saves lots of money. But not every employer realizes this, so employees suffer. Often the ones who suffer from the least flexibility are the ones who need it most. This inconsistency usually hits hourly or low-income workers the hardest. These are the people who are least able to go elsewhere if they're unhappy. These are the ones who are most desperate for every dollar, and the ones whose industries are least likely to budge on time requirements, no matter which company they work for.
Some nations have laws requiring some type of flexibility: paid sick leave, paid parental leave, discrimination against part-time workers prohibited, etc. Many employees on this side of the Atlantic envy these kinds of rights.
But it's not a straight-up, apples-to-apples comparison. Work culture is different in the United States. Employment law is different. Employer expenses are different. Medical insurance, liability insurance, and C-suite compensation can rack up much more here than they would elsewhere.
In nations where nearly every working parent takes advantage of paternity leave for months at a time, employers are much more likely to have systems in place to deal with employment gaps when they occur more regularly.
When it's not universal, flexibility is harder to come by. Employees have to depend on their own employers if they want flexibility, and many employers have not seen the light. I think it's unlikely for flexibility to become universal without laws to protect it; however, I also think that we need to ask for it.
The more we ask for it, the more popular it will become.