Here's Where It Gets Really Interesting.

Fisrt of all... In terms of code. I consider very little Arduino library code what I would call production quality. In my experience the higher level code seems to not be compact, efficient or robust. The exception being the GCC AVR libraries (std...) and tools which Arduino is ultimately based on.

And Yes. I do use said libraries. But there is a big distinction. Non of those projects are what I classify as demonstration prototypes. Although most are constructed very well they are all considered 'proof of concept' breadboards. A.K.A. First generation tests/demostrations... Not quite ready for prime time.

Which brings me to the second and probably most important point. Most failures occur because of poor assembly of the prototype. Especially contacts (connection points). For most new experimenters the only exposure (training) they receive is from YouTube. Too often, sadly, the demonstrations are not about good engineering techniques but instead are focused on instant gratification. Really... Anyone can buy a couple of sensors, some jumpers and an Arduino from ebay, follow a tutorial (based entirely on someone elses work) and create a great video presentation. And that's the point. Good for one demonstration only.

So What's The Problem.

In a proper development environment the use of solderless breadboard and jumpers proves useless for demonstration. Not only is the bulk of the project intimidating but the reliability is generally horrible. Both eventually leading to a failed attempt. In fact. Unless there is extreme question how the circuit will behave then NO professional (or even serious hobbiest) would use these techniques.