If an employer is allowed to contribute up to 38K (57K-19K) to your 401K through a match, why don't we have an option to deduct the extra 38K from our salary and count it as the employer match in order to contribute pass the 19K limit?
There are rules regulating "fairness" amongst all employees in a given companies 401k plan outlined here: https://www.irs.gov/retirement-plans/plan-sponsor/401k-plan-overview
Although your proposed scheme may be possible in some circumstances, I would expect that those rules would be difficult to skirt around depending on the distribution of employees that opt for your "mega-match" and those that don't.
Jumping outside the framing of the question: Even if you cannot get a "mega-match", you can get a similar tax advantage if your 401k allows after-tax contributions and in-plan conversions. In this case, you can contribute (after-tax) the allowed remainder up to the combined $57k, and then convert that balance to a "backdoor Roth 401k". You will not owe tax on those contributions or their earnings when you withdraw them in retirement. Although you don't get the immediate tax deduction, you effectively put away more this way because a dollar left over after paying taxes is worth more than a dollar yet to be taxed.