And the difference here is that the 'tax' the employer pays lessens or disappears as employees get used to working remotely; whereas for the employee, there will always be a cost in time and money to commute.

With employees working remotely, the employer can also make big cost savings by needing a much smaller office space.

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...)

The employer is paying for it, it just isn't clear what ledger column the cost appears in.

If an employer isn't paying me enough to cover travel costs and another offers work from home, it is a reason to switch jobs.

I suspect that and a dozen other tiny reasons are why work in office jobs tend to pay more than work from home jobs.