The infringements data seems to indicate that it is guys without GPS or digital planning tool of any kind who are vastly more likely to infringe. Imagine a scenario where a pilot gets all his carefully drawn lines on his paper chart (just as he was trained to do), and flies his plan exactly right - but oh no! he is using a paper chart where every AIRAC amendment and NOTAM has not been carefully annotated since the chart was published, and his perfectly planned route flies straight through airspace he was unaware of.
Furthermore, having GPS on board can be a godsend when accused of infringing; I have heard a number of instances where a controller has insisted CA has been breached and subsequently started "the process" for raking the pilot over the coals - but then the pilot produces his track logs and can demonstrate exactly how well outside the zone he was. Without GPS you have pretty much no right of reply when accused of infringement, and no warnings popping up to notify you before the infringement happens, so infringement is more likely.
The times GPS is not so helpful is when the pilot doesn't understand how to set the warnings appropriately, when he doesn't update the aeronautical data, and when he doesn't appreciate the nature of GPS error and the conditions under which GPS functions sub-optimally. This could be remedied by a few hours briefing as part of the PPL syllabus - GPS is a tool, not a magical anti-infringements device, and we need to make sure that the benefits and limitations of the tool are well understood to optimise its effectiveness.