Take off about $20k from that (conservatively) because of taxes. And you still have to PAY for your benefits. They're not free. They come from your paycheque. I pay over $150/month just for my family's health insurance.
Then add things like car insurance (~$2500/yr), mortgage payments (~$15-20k/year), house utilities (gas,electric, water, etc) - ~$300/mo, other necessities (cell phones, internet, home phone, cable, etc) - ~$200/mo, food ($200/mo), and other things that I've probably forgotten..
You can't live off $54,000 comfortably if you have responsibilities like kids, house/car payments, etc.. If you live alone or have another person making that amount, then sure.
But that doesn't take away from the fact that kindergarten teachers don't make anywhere near that amount.
If you honestly think you cannot live off of 54 thousand dollars a year you are REACHING. You could live off of 30 grand a year. And not all jobs make you pay for your benefits. I've always had to pay for mine but both of my parents have jobs where that s**t is just included free of chrage.
Also that 20 dollars an hour average is higher then it should be. That is greatly bumped up by the hundreds and thousands of CEO's making millions of dollars per year.