You can look at employment rates in countries with generous social welfare and unemployment benefits, and notice that the percentage of the population sitting idle who are not sick is minuscule, and not significantly different format the idle population in countries with weak unemployment benefits.
It is true that there are systematic exceptions - especially people born rich.
According to the OECD, productivity per hour worked [0] in Scandinavia, Belgium, the Netherlands, Luxemburg, France, Germany, Austria and Switzerland is comparable to the US, and in some cases significantly higher. All of these countries have much more generous social safety nets.
The average hours worked are significantly less for those small upticks in PPH. If you factor in hours worked, the US comes out far ahead of most if not all.
What does productivity have to do with people's choice of working or not? We were discussing whether people need encouraging to go to work or not. Productivity is a completely different metric, impacted by many other things.
Productivity is a part of the metric which you base that decision on. Do people need encouragement == will we produce 'enough' with less encouragement || is the long term reduction in production, and it's effect on future generations worth the increase in leisure time now.
It is true that there are systematic exceptions - especially people born rich.