This function, in the last paragraph of the article says it, is only for paid versions. Yes, there is a trial version with many functions but not all.
Yes, but it's usually for personal, non-professional or business use. If you want to distribute it to sell, as in the case of Yuneec, this is not the case, you have to pay and the same thing happens with Ardupilot. Anyway, within the Dronecode project is involved and Yuneec has access to it.
For now, as far as we know, the only application approved by Yuneec to control the H520 is Pix4DCapture. I understand that if the orders you give to the drone are valid, do not make those orders crash the drone should not be a problem, another thing is that for lack of integration these orders are wrong and cause an accident, then Yuneec would only cover the failures of their own aircraft and this would not be the case.
The fault is the software, not the hardware. The Dronecode project is the one that has to develop the software base and then the manufacturer, in this case the team of programmers that Yuneec has in Switzerland, develop DataPilot. And this is where the problem seems to be. Either they don't find the key to do it well, or there is no coordination, or the tools provided by DroneCode are not powerful enough, or who knows ??