Considering how many years Hydraulic systems have been in use & how many of those systems were/are 100% trouble free & how short the track history of EPS systems & how many known failures have occurred you'll have a hard time backing that statement up with facts....
Cheaper to produce, sure..
Easier to vary the assist level, sure..
More compact packaging, sure..
More reliable? evidence doesn't support that.... Yet... And considering how cheaply manufacturers want things produced these days I doubt it ever will...
Well, they've been standard on various models for about a decade now (longer in some luxury brands), and there are very little problems......
Keep in mind, despite hydraulics being around for 60+ years there are still plenty of them having issues out there on newer model cars. Whining/leaking pumps, leaking pressure lines, racks, rotted out return lines, etc. And plenty of those were well within the few year warranty period.
There are far fewer components and moving parts in an electric system, and no fluid to leak out.
I cannot count how many low mileage whining Ford P/S pumps I've changed, but I can tell you how many electric racks I've replaced - 0.
If these were only out for a year or two, I'd also be more skeptical, but they've had plenty of time to accumulate mileage across a wide range of platforms and drive cycles.