How Many Doctors in the United States Work for $17.61 an Hour, or Less

Just curious, since Marketplace radio told listeners about the shortage of workers in the residential construction industry for jobs that pay $17.61 an hour. Would we be hearing that there is a shortage of doctors (or lawyers or economists) if few were willing to work at $17.61 an hour?

I know these professions require much more training (although construction workers seem to do much better at their jobs than economists), but if the wage on offer for jobs in these professions was ridiculously...