If it was to match inflation it would be more than $15 [2] And if it was to match productivity, it would be even more [2][3]
[1]https://www.epi.org/publication/labor-day-2019-minimum-wage/
[2]https://edition.cnn.com/2021/02/21/politics/minimum-wage-inf...
[3]https://cepr.net/this-is-what-minimum-wage-would-be-if-it-ke...
Neither of your sources support that claim:
> Even worse is that federal-minimum-wage-earning workers today are paid 31% less than the $10.54 an hour they would have been paid in 1968, when the minimum wage reached its highest (inflation-adjusted) value. [1]
> The wage hit its peak in inflation-adjusted terms in 1968 at just over $12 [2]
The productivity argument is silly, and your third source says as much. Minimum wage has not kept pace with average productivity because minimum wage jobs themselves have not kept up with average productivity. CEPR makes the argument that doctors and software engineers just make too much money, and this somehow hurts the minimum wage earners. Which is a wild bit of mental gymnastics to claim that minimum wage earners should profit from high-skilled productivity, but the high-skilled workers should not.
Tying it to inflation though is a no-brainer. We do it for social security payments, congress salaries, etc. There's no justifiable reason for not doing this.
A wage crush is ideal, not a wage raise.
This would also mean that many people who are not even remotely close to "the billionaire class" would get pushed down, so it's not really popular with high-earning coastal liberals, and probably many people here.
Someone smarter than me will have to come up with something. Right now though it's a runaway feedback loop that's going to eventually destroy itself by "doing everything right".