for those who offer service only in very low rate;
they see themself like factory workers,
thou the rate is cheap, but bear in mind that they don't need 5DMKIII, or D800E
they don't use pro lenses,
don't shoot with two bodies with prime lenses,
don't shoot RAW,
don't need many pieces of 32GB memory cards
don't need photoshop or lightroom
don't need highend computer,
don't need calibrate monitor
don't need bring notebook to go for shoot,
don't need spend hours and hours post processing
don't need run here and there to find creative angle
don't need go high and low to find interesting viewpoint
and they also don't need to meet up with customers,
don't need to exchange 20-30 emails before confirm a shoot,
don't need spend money to create and update hardcopy portfolio,
don't need create fancy website and pay advertisement,
don't need to join professional and trade associations
don't need to attend workshops, seminars and conference
that is how they can maintain very low overhead and charge so cheap,
have all the time they can and shoot day after day.
that is nothing wrong with this, just the way they position themself in the photography business.