Why can't the RPi have at least 1GB or 2GB of flash storage on its board? My 4 year old, 80 euro android has 8GB.
It's not a secret SD cards quickly fail.
I've not bought the RPi for that specific reason. Even if the RPi is 5 times slower, having reliable storage seems seems like a most important feature.
Because forcing everyone to pay a chunk more money for on-board storage which not everyone needs is unnecessary. Their decision shows that cost is a more important feature and I don't think that should come as a surprise, there's plenty of stuff out there justifying the various decisions and it all comes down to cost.
I'm guessing if the RPi Foundation went that route with the Pi 5, it would be similar to the Compute Module where there would be a cheaper 'Lite' version without eMMC then more expensive ones with eMMC.
One of the main reasons SD cards fail in a PI is shutting them down incorrectly.
If you pull the power cord you risk corrupting the card.
If the PI had a proper power switch system (also omitted due to cost) then you would see less SD cards being corrupted.
It is possible that even on-board flash memory could be corrupted by improper shutdown, and if that happened the entire pi would be useless, not just the SD card.
You have the Compute Module versions of the pi with embedded storage.
The reasoning behind the SD cards on the consumer pis is that they are quick to swap out, and don't have the problems that "bricking" the OS could get you into with booting from onboard storage. There is the possibility to use USB booting in the latest boards (certainly with the 3+ not sure about the status of the 4) which has a flag set in the onboard eeprom so you can use external SSDs/USB drives.
With USB boot it's really nice for me, as I have a few microSD cards preloaded with 'boot up and do X' tasks, as well as a couple SSDs which are set up the same way and I can just remove the microSD and plug in the USB drive.
It's not a secret SD cards quickly fail.
I've not bought the RPi for that specific reason. Even if the RPi is 5 times slower, having reliable storage seems seems like a most important feature.