The second link refers to the "black economy", which includes, for example, a housekeeper getting paid in cash without reporting it to tax authorities. The first link also includes "using cryptocurrency to hide financial activity, such as evading taxes or operating an unregistered MSB", but I doubt many housekeepers are using Bitcoin for that. In my opinion, it would be more interesting to compare the statistics on payments for activity that is itself illegal (regardless of whether it's taxed or not).