This happens in the USA all the time.
Yeah, I have seen it here myself but what I have also seen is a lot of folks who have paid social security taxes for thirty years and when the doctors tell them their body is falling apart and they should be on disability they are turned down for benefits and wind up unable to hold a job and with no benefits. For every person I have seen drawing disability and working I have seen several who have been turned down for benefits but are unable to work. You cannot tell what a person is experiencing by their appearance. I have never applied for disability but I went through a period of years when I walked around in agony every day. I was fortunate to have my own business at the time so that I could decide when I had had enough and take a rest. Had I been working for someone else I am 99 percent sure they would have found a way to get me off the payroll and I would never have found a decent job again.