Drug Testing for Government Aid

There are a good number of states now requiring mandatory drug testing for people to receive government aid.
I am not opposed to this stand, but it worries me.
This stand allows the government to step into our lives and tell us what we are worthy of receiving.
I hear the cry from the hardworking people stating they must take a drug test to get employment.  Well it is not the company requiring the drug test, it is the insurance provider of that company that does not want to take a risk on a drug user.  I understand completely, but for the hardworking citizens to claim they have to take a drug test in order to be employed is slightly incorrect.
This cry that I hear also comes with a preconceived notion of those receiving aid.  Most assume people receiving aid are lazy, wishing to just ride on the coat tails of those hardworking citizens.
There are probably an equal number of people receiving aid who wish they did not need that aid, as those who wish to ride the coat tails and be jobless.    You can not just speak to those who wish to be jobless, the words and actions of those making bold statements hurt and shame those who honestly need the assistance due to their situation.
I agree that government aid needs to be spent on what it should be spent on (food, housing, utilities, gas to seek employment or further education), but in taking away the right to aid for those that truly need it (children) is taking away security in knowing they will have a meal, heat, and a roof over their head.
I understand that many states will continue to send aid to a family member who will care for the child, but that means pulling the child away from a home environment that may not be as bad as those hardworking citizens assume.
I think it is a fine line. 
The government starts drug testing to ensure government aid is not being spent on drugs.  Well, then there is always the same aid being spent on alcohol, cigarettes, unneeded home decor, unneeded clothing, hair accessories, tattoos, cable....where does it stop???
How much do we let the government invade?