"workers are better off" is a statistical nonsense regardless of what's written in that pdf. This type of arguments can convince only non technical or not very smart people. A proper analysis would split workers into subgroups and give specific numbers for each subgroup. A proper analysis would use words like percentiles, median and distribution. When I see that "something is better on average" I always think that I'm being lied to.

That's just his/her paraphrasing of the complete source - if you actually had read that one you would see that it does give specific numbers for subgroups.