Even in 2009 the adjustment wasn't sufficient to bring minimum wage back to 1970 levels, adjusted for inflation. Picking the last rate change isn't a good way to measure minimum wage.
In inflation-adjusted dollars, in 1970 the minimum wage was $10.66. So it is very accurate to say that the minimum wage has eroded due to inflation; currently it is $7.25, which is significantly lower.
Some Democrats propose raising it even higher than it was in 1970, but that doesn't refute the claim that modern, current minimum wage has been eroded — it has, significantly.
You've cherry-picked the highest (adjusted) minimum wage over an ~80 year period. The average is closer to $8 in current dollars, which is actually below the inflation-adjusted 2009 figure of $8.70.
That's not cherry picking. (Adjusted) minimum wages are raised to their peak, and then are gradually lowered due to inflation. If you're picking a point of comparison for the proposal to raise the minimum wage to a new historical peak, it's natural to look at the last time it was raised to a new historical peak.
To look at it another way, even if the 15$ minimum wage is passed, that doesn't mean that the future minimum wage will be 15$ on average.
Picking the highest of the highs over 80 years is the definition of cherry picking. Why not simply pick the average over time? Or any other peak if you desire peaks?
Picking 1970, before many women entered the workforce and competition was more global, is likely not a good value to pick. It's probably better to let states, which have vastly different costs of living, set state or local wages to account for those disparities. Forcing a mom and pop in the middle of nowhere to pay what a worker in NY or SF gets by law will hurt many.
In inflation-adjusted dollars, in 1970 the minimum wage was $10.66. So it is very accurate to say that the minimum wage has eroded due to inflation; currently it is $7.25, which is significantly lower.
Some Democrats propose raising it even higher than it was in 1970, but that doesn't refute the claim that modern, current minimum wage has been eroded — it has, significantly.