> Across three RPis, I've bought about seven SD cards, and from everything RPi users tell me, that's a totally normal failure rate.
Sounds about right. I went through maybe 4-6 cards on 2 Raspberry Pis in a year and a half.
> I'd love someone knowledgeable to explain why this happens. According to general opinion on the RPi forums, it's because SD card manufacturers cheap out all the time
SD cards are basically uniquely ill-suited to be used in a Raspberry Pi.
First off, cheap SD cards have no wear levelling. The flash controllers are super primitive. They are designed to be written sequentially until full, and erased, like you would use a camera. A regular Linux operating system is not designed to moderate its writes, it will happily do all kinds of work and logging on /var and other places, doing tons of heavy random writes that put tons of wear on the card (write amplification/etc), and there is no levelling taking place. The flash cells just burn out.
Real mobile OSs are much smarter about what they write to flash, and they have eMMC that usually has at least a slightly smarter controller optimized for more random-ish loads, and/or is totally under the CPU's control with a filesystem designed to work with flash.
Next, flash doesn't like to be powered off during erases or writes. In some cases it can actually corrupt operations that were successfully completed. The flash cells do not get as much charge as they should and can decay prematurely.
Nor does flash like operating under questionable power conditions either. The flash can think it's successfully completed the operation, the processor will keep on trucking, but if the voltage drooped too much, the write doesn't persist. In some cases, this can cause the flash to get trapped in a "bricked" state that needs a hard reset to clear properly (which can't be done with a SD card).
http://superuser.com/questions/290060/can-flash-memory-be-ph...
The Pi also has no/very little power filtering. Your phone doesn't ever run off the charger. It uses the adapter to charge the battery and/or feed the regulator circuit, the key being there is a regulator circuit here. The Pi does not have one.
In short - the Pi is an absolute worst case in terms of power. Your average camera or phone has a battery, so the power is clean, full-on power faults are quite uncommon, and the device can monitor voltage and stop doing writes before things get critical. Not only is it really, really easy to accidentally or purposefully unplug the Pi, or flip the power strip off, but the shit-tier phone chargers that get used with it have terrible power filtering and tend to have wildly insufficient power delivery capacity. Under load, the voltage droops and the noise on the power line gets pretty intense.
With the first-gen Pis, there was an additional physical issue with the SD cards. The cards are just made of plastic, they are meant to go into a slot in a camera or phone that physically supports them, they are not intended to just hang off into space. The Pi does actually get fairly warm, especially if you have it in a case, and hot plastic warps. The card loses contact half-way through a write and there goes your file system.
http://likemagicappears.com/2014/03/11/sd_card_issues/
https://www.raspberrypi.org/forums/viewtopic.php?t=39843&p=3...
https://bigdanzblog.wordpress.com/2015/01/27/raspberry-pi-fa...
Adding a "UPS" board that can command a soft-poweroff, a decent microSD card (Samsung EVO are reputedly the most reliable on a Pi), and a "low-profile" microSD adapter that doesn't hang off into space quite as much reportedly make a pretty big difference in reliability, as does using a purpose-built adapter from a reputable vendor like Adafruit or something. Not running it in a case probably helps too.
Again though, once you spend the money to fix the flaws, you could just buy something that just includes what you need to boot up right in the box.
I really can't emphasize enough how much all of this is actually the result of poor design. If the Pi Foundation would have chucked a 2 GB eMMC chip on there and added a barrel connector and a decent power supply, these issues would be essentially eliminated. And IMO the issues are pretty much show-stoppers for any chance of reliable operation.
> In regards to cheap whiteboxes, no such options allow access to GPIO ports. I've learn plenty of interesting things about soldering circuits by having these, without considering the Pi a PC learning tool.
That's definitely true, but you can also buy a Bus Pirate that will be capable of adapting most simple embedded units to any PC.
You really only need the Pi's GPIOs when you are doing something that involves really high throughput or really low latency. The examples I've heard are video streams and using a GPS board as a reference for an NTP server - they exist, but for your every day "talk SPI/I2C to a sensor" or "count freqency counts from a sensor" the Bus Pirate does very well.