Why is 30 "way too much" but 15 is OK? Or is 15 way too much too?
Well first of all I decided look where this $30 minimum wage thing came from. To no surprise, it's a right wing talking point.
Raising th minimum wage to $30:
"Intuitively, most everyone understands that raising the minimum wage to $20 or $30 an hour would have devastating effects on the employment prospects of less skilled workers: unemployment rates would skyrocket within such groups, so we see no serious proposals for increases of such magnitudes. Raising the minimum wage to only $10.10 would have much milder effects that might be difficult to detect in the aggregate – though such effects would still be noticed by employees who received raises or lost their jobs."
Ask an Economist Department of Economics
The above explanation basically covers why nots.
Now, the right likes to scream that raising the minimum wage to $10.10 would raise inflation and cause massive layoffs.
However, checking out historical facts one can see that facts don't back up that argument.
If one has the ambition, they can go to these sites which cover when historically the minimum wage was increased, the inflation rate (CPI) historically month-by-month and the historical unemployment rate month-by-month.
All a person has to do is match when the minimum wage went into effect and then match up the rise in the CPI and the unemployment rate. The conclusion is that there were no spikes in inflation or the unemployment rate.
Minimum Wage - Wage and Hour Division WHD - U.S. Department of Labor
Historical Consumer Price Index CPI
US Unemployment Rate by Month
The only time there was massive layoffs was during the Great Recession. Not one economist every blamed the increase in the minimum wage for the layoffs, plus inflation was completely flat and there was actually deflation.
Regarding your question about a $15 dollars minimum wage, if a city want to raise the minimum wage, it usually tied to the fact that the cost of living within a city is higher than it is in rural areas. That would be a judgement call for the city entity.
Also, I'd like to point out that increasing the minimum wage certainly does help the middle class per the Cato Institute.
Minimum Wage Hike Would Benefit 3X More Middle-Class Workers Than Poor
Minimum Wage Hike Would Benefit 3X More Middle-Class Workers Than Poor