The design and enforcement of the systems is many times at fault. I can't speak for the UK, but in PR as well as in the US, benefits for the unemployed can sometimes dissuade a person from working depending on that person's pay scale. There's a fine line between working one or two jobs while barely being able to pay your bills... and claiming benefits that may be 5% less in total (or 5% more)... and not having to work. That's where the mentality of the individual kicks in. If the system makes it tough to decide, something's wrong.