I will say that user error is the cause of most problems.
after I sent back my blue flasher, I haven't had a single issue with mine except for the ocassional temp light.
User error is the most commonly assigned cause to all problems, ever. 89% of the time it's the incorrect assignment of cause, and generally a contributing cause at best.
As far as the PAX goes, if you are following the user manual, you are not committing a user error. By definition.
So even someone who crowns the device the champ, had a flashing light error AND has temp light issues.
As you described, the iso evaps, leaving resin, causing the sticky. That is not a user error, that is a design flaw as the root cause of the problem.
Further investigation of the design and the symptoms reveals other items, like the fact that the PAX is charged upside down, gravity, liquid ISO, then evap... and we can see an obvious failure path.
Think about it this way, back in the old days ATM machines would sometimes spit out money, and then your ATM card. A lot of people would forget the card, because they got the money (Banks tracked this, replacing cards was very expensive for greedy banks, so they looked into it).
User error right? Lets analyze. Typically ATMs now will give you back your card first then the cash. Because you are far less likely to forget the cash, as that was the reason you are using the ATM in the first place. Having it give the card back first, has resulted in far less cards left in the ATM as a problem.
So did the users stop committing errors? They changed the process and design, which addressed the root cause, and that in turn reduced the errors.
RCA and Quality system methodologies are vital in MFG. PAX is a v1 product, it is likely that v2 will address most of the defects because that reduces Customer Service cost.
Calling it 'user error' would actual hurt the brand long term if that was their plan (doesn't sound like it is, my CS session never even touched on any user error) as that would imply it's complicated to use and maintain. Like owning a BMW... And would not lead to any improvements.
XBOX 360 RROD is another well known story of "user error" that really wasn't anything at all to do with user error, even tho that was where the blame initially went.