To resort to cliche, F1 cars are rolling R&D prototypes and have all the problems associated with operating the 'Mk 1' of anything.
While some parts/systems are tried and tested and would be reasonably interchangeable between teams (springs, dampers, radiators ect), there are many elements/parts/systems that are bespoke, one-off, "lets see how this works in this configuration" made-for-the-purpose kind of thing.
As bot6 alluded to, many (most?) parts are worked to a reasonable approximation of their engineering limits. When everything goes as expected, and is operating within their narrow band of tolerances, its fine. Step out of that zone of tolerance and there isn't far to go until failure.
I'm actually surprised that there aren't more spectacular failures like the one Buemi suffered in China last year. Sympathetic failures are nasty!
Plus, most teams are running custom software packages. I never met a bespoke programme yet that ran bug free. Even one that manages a car at 300 kph.
Besides, most F1 cars are manufactured in the UK or Italy, and its not like either country has the best reputation when it comes to reliable vehicle electrics.