MIT claims that about $35/hr would be a living wage in almost every part of the USA. So that's our "high" point for thinking about this. Currently, it gives $23.06 as the figure for my nearest city (Santa Fe), $28.08 for NYC and $20.16 for Manhattan, KS. I've seen people disagree with these numbers.
https://livingwage.mit.edu/
Do I think there should be jobs that would only be done in the context of parentally- or other-provided housing, food and clothing? I'm not sure. I lean towards the answer being no, but could be convinced otherwise.
I still don't agree with your 40 year take on this. When "fully grown adults" started flipping burgers, it was because you could live on the income that provided. Now you cannot (and ditto for lots of other minimum wage jobs). It was not the case that these jobs were "teenager only" and people took them even though they were impossible to live on, 60 years ago. They took them (slowly, over a period of time) and they gradually changed from teenager only work into "real jobs", and over a slightly longer period of time no longer acted as viable living wage work.
That said ... sure, the income levels for the lower 4 deciles of the population haven't kept up with things (until very, very recently at least), and this means in part that new jobs at appropriate (lower, but still livable) wages have not been created at sufficiently high rates.
> "Increasing the minimum wage to be a living salary of $40-$50/hour would eliminate many opportunities for people entering the workforce who can't justify that kind of investment currently".
Firstly, as I indicated above, I don't think it has to be that high. Secondly, I think that if there are "opportunities" that cannot afford to pay a living wage, I'm not sure anyone is foregoing much by them not existing. To be clear, what is meant here by a living wage is something that a full time job pays roughly 3x the local rental rate for an appropriately sized studio (perhaps 1BR) apartment in reasonable quality.
> Leave it at the market-clearing level of $20-$25/hour
"Currently, 34 states, territories and districts have minimum wages above the federal minimum wage of $7.25 per hour. Five states have not adopted a state minimum wage: Alabama, Louisiana, Mississippi, South Carolina and Tennessee. Two states, Georgia and Wyoming, have a minimum wage below $7.25 per hour."
There is not a single state that has the "market-clearing level" you mention, so "leaving it" there seems impossible. Tukwila, WA is the only city in the country with a minimum wage above $20.