They actually do track SE photographers. It's on the Outlook tab. The specifically mention the difference between "salaried jobs" and SE.
My Canadian stats show similar and do track SE:
Photographers - Service Canada
Pay is absolutely dismal. Most people cannot survive on a photographers wages. It's a second or "hobby job" for most.
Sears shut down the world's largest photo studio network and the pay for photojournalists has either gone to zero (Chicago) or been substantially reduced (38% where I live).
While pro photographers are an important driver of product development for the industry, image sales are way, way down (actually mentioned in the Getty consolidation). That means there are far fewer earning income from taking a photo. Period. The prosumer has access to the same tools and produces competing IQ. Pro quality image taking is well within reach of so many more people because of digital. And photography itself is declining in segments (journalism, product photography) due to video, CGI, and amateur content supply.
It's not going to disappear, but it is a struggling, very low pay vocation dominated by part-timers who are simply trying to sell photos to pay for equipment; this is known as a self-supporting hobby in economics.
Pentax cannot count on a pro segment buying its equipment (645D excepted and that's maybe 1,500 units/year...maybe). It's the hobbyist who drives gross revenues where Pentax has to sell.
Bluntly put, the # of Pentaxians willing to pay more for their next camera is a tiny fraction of our already small market share. If the last flagship was US$1,599 then the FF flagship needs to be there as well. Pentax doesn't have the lenses or accessories to go above the D600/6D category.
Gaps in the lens roadmap, flash system, macro, tethering, connectivity, accessories, software, superior AF, third party add-ons, etc. all make it less likely someone will pay MORE for a Pentax than they already do. If Pentax cannot offer the full FF feature set in a SYSTEM camera, why design and price a product there, especially when sales are stalling?
A high-priced, weak system will go nowhere, selling too few to current Pentaxians and able to lure zero new entrants or brand hoppers.