There always will be scroungers, at any level of society, con men and scammers, blackmailers, anything not to earna living.
Similarly there are just as many people entitled to benefits who do not claim them, through ignorance or because they are too proud to. I worked for Age Concern, as it was known then, as a volunteer Home Advisor for 10 years and time and again I dealt with people who were living in desperate conditions who were not claiming the benefits they were entitled to, and unwilling to do so.
I also took to appeal cases where benefits had been refused. On appeal, well over 90% of claimants were granted the benfit they had applied for, but some just refused point blank to apply for either Attendance Allowance or Pension Credit.
For every cheat there is someone who should be receiving benfits and isn't.
If any one can devise a system that both catches all the cheats AND gives benefits to all those entitled to them. there is probably a knighthood, if not a Life Peerage awaiting you.