DW began with the premise that legal immigrants are a benefit to society, but then stated that he saw no benefit to undocumented immigrants.
I fail to see any difference in terms of benefits. Actually undocumented immigrants cost us less as they are less likely to take full use of social services. They are also, statistically, less likely to commit felonies. By any real measure, they are among the least costly, most contributing elements of our society.
You rely heavily on that one study that I have raised questions about in the past only to have you fail to respond. It may be that your study is accurate, it may not be. I note that it did not pry apart illegal and legal immigration. Also, while it speaks to government resources, it does not speak to private resources well, the costs of unpaid hospital bills or insurance matters absorbed by others. It does not go in depth to lost schooling opportunities for citizens. It fails to account for the impact of crime which is greater than financial alone, and it ignores the incredible number of fugitives from justice we have. until those fugitives are accounted for we only have a partial accounting. As for them being les likely to commit felonies, they are I believe les likely to be convicted of felonies both because they can flee across borders and because illegal victims under report things. Still there is an appeal to the argument that most have substantial incentive to comply with the law so though neither you or I know this to be true I more or less accept that it is so. What I do not accept is that they commit crimes at a lesser rate than legal immigrants who also seem to show greater respect for the law than do native born folks.