You mean "they", and you mean "a majority". And the Constitution of THIS particular country was written to protect the minority from the ravages of the majority, and oh, by the way, the Welfare States is a violation of the Constitution. Therefore it's not supposed to be happening regarless.
Whatever, since free handouts isn't a right, since contraints are already in place on their disbursement, drug testing is nothing more than another constraint.
The government requires proof of income level, bank statements, pay slips, unemployment records, what have you. It's clearly just as big a violation of the Fourth Amendment to demand these documnts ("papers") as it is to demand a drug test ("persons"). No more so, no less so.
Yet you accept the one but not the other.
There's some other reason you're objecting, since whatever ever it is isn't logical.