It's not a fixed 20% per player, it's 20% overall. Seeing stats for yourself wouldn't help because for every time you have a streak that "shows" a 10% chance, someone else has a streak that "shows" a 30% chance.
Purely luck-based systems are bad from a user perspective but that doesn't mean they're broken.
Basically imagine that every time you RE something, it's rolling a random number 1-5. You have to get a '1' for it to RE.
The probability of RE'ing 20 things and not
learning a schematic is pretty small, but it doesn't change the fact that probability each
time you RE of being 1-in-5 chance.