Two items to your central question of, as I understand it, "how is it a lib thing"?
First, in the meme's title, I expressed that it doesn't matter to libs what the maths say as long as it feels good. Percolate on that and prove me wrong.
Second, as CB said, it is two entirely different issues whether the voters of a state say that they want their minimum wage to be X or if LIBERALS in charge of the executive and legislative branches ram it down the throats of the entire country. The voters in Florida know best what works for them. They're not trying to control other states.
Please tell me in your educated mind what good $15 an hour does at a national level? You are aware that the cost of living in Detroit, for example, is way lower than NYC, LA, or Miami? I could buy a 3 bedroom house in Detroit for $10k but I couldn't rent a studio apartment in one of those cities for that. So what good does $15 an hour do in those cities? It's just an arbitrary number that sounds good. Why not make it $50 or $100?