Earlier quoted context omitted.
What penalty? it's the other way around, you take a 20% penalty if you stop working, and note that it's not for people who voluntarily stop working.
You can easily save 10 to 20% when unemployed because you don't have to pay for daily transportation (tube/train/car), lunch outdoors every day and a few other things. So the difference in disposable income is about null in most cases.
Given a lack of choice how can paying wages make any difference to their employment behavior. I'll repeat: this is not basic income.