It's not that I don't believe it is likely, it's more like I don't like spreading an unqualified stereotype that I haven't actually validated in any way other than personal anecdotes. It's not like it's a terribly harmful stereotype (at least, I don't have anything against day laborers at all) but just as a matter of good hygiene I believe it's good to hedge a bit when you're spreading information that is essentially folklore. (In this case the point was to spread the folklore part, so I didn't feel it necessary to go and try to validate it with data myself.)