Employer contributions are tax deferred, not untaxed. Assuming you don't trigger penalties, you'll pay ordinary income on that down the line. I wouldn't expect to retire into a 0% tax bracket, especially if you're maxing the employee contribution.
Capital gains are taxed as ordinary income when withdrawn from the 401k. The timing is better (since you're not taxed on sale, you can rebalance at will), but the rates are worse than a taxable account.
I'm just saying, if you count employer 401k match in your all-in comp figure, it doesn't make sense to treat it as untaxed; it will be taxed, the rate might be less, but it might not be that much less.
You can put the employee contribution into Roth, but the employer contribution is almost certainly going into traditional; I don't believe there is a provision for employer match into Roth.
Unlike the employee's contribution, however, the employer's contribution is placed into a traditional 401(k) plan, and it is taxable upon withdrawal. The employee's into a Roth 401(k). Therefore, many employers have found the additional administrative demands of offering the Roth 401(k) outweigh the benefits to their employees and do not often offer one. This is the reason for the perception, or misconception, that employers cannot provide a match to Roth 401(k) employee contributions, when in reality, they are simply not providing the option for the plan at all due to the administrative hassle.
