"Where are my 4 hours owed for the day I was sent home???"

Is this a myth or is this fact? Are employers or agencies responsible for paying workers 4 hours or half a day if they have been sent to job and then sent home due to over staffing, etc?
Working at an agency you will hear this question come up and not too many recruiters, dispatch, etc do not know the answer to this question! To save you time I will give you the short answer and it is "No!" However, if you want to know the reason or laws that answer this look no further than the paragraph below.
According to FLSA handbook for Illinois,"Illinois law does not require employers to pay employees for reporting or showing up to work if no work is performed. An employer is also not required to pay an employee a minimum number of hours if the employer dismisses the employee from work prior to completing their scheduled shift. Employers are only required to pay employees for hours actually worked.
This paragraph from above is in regards to show up time or reporting time and a link will be placed below from the source in which this information was provided.
Is it fair to send workers knowing that majority of workers will be sent home? Most likely not, however, agencies must compensate for percentages of workers that will not show and in some cases will oversupply businesses with workers.