Assuming that employers don't pay for commuting is a bit much. More stressed / sleep-deprived / commuting-fatigued employees are less effective at their jobs and, crucially, for the cases in which someone commutes while still spending all their desired time on leisure and sleep, then the commute time is clearly one-for-one substituted for work time.

There's plenty of research as to the negative effects of commuting (e.g. https://www.psychologytoday.com/blog/urban-survival/201501/c...)