RAM may have a low error rate much better than HDDs or SDs. That does not mean that you won't have errors even if you have a good brand and treat it well. Bit-level errors can and do happen all the time without us knowing; other times it happens in the wrong place and we notice (but think it is something else) it isn't until it gets really bad that we notice.
Example, say your RAM has a 1% bit loss rate (ignore that is insanely high) well if 90% of your data is not touchy code but data, the odds are that you may not notice 1 bit getting flipped that often. Then you have the fact that RAM could maintain that error rate over decades of smaller faster RAM but now you are storing MORE data and cycling it MORE than was possible on the older computers. So, if you had 1 bit error every gigabyte of throughput on a slow 1Mhz computer with 1MB of RAM it would take a long time for that 1% bit flip to happen (and if you noticed you'd still not likely blame the RAM) -- but today pumping though in seconds what that old machine would take a year; the error would occur quite often. SAME problem with storage but with an additional problem in that they still have the same lifespan requirements - RAM can be refreshed can checked.
Something else to be considered, the error correction schemes being used today are being pushed by the demand for higher density storage. Your HD isn't doing huffman or any of those old simple bit recovery schemes they've moved beyond that long ago to the next gen stuff from what your 56k modem was doing to fight phone line noise. They could make it better... but you would be giving up significant storage space. Perhaps somebody with a good marketing scheme and enough upset consumers could get you to pay MORE for less storage space... I know I would buy into it.
Essentially, we are at a point where HDDs expect you to scrub them for errors every year to avoid the bit rot... which is what I now do... haven't detected an error in years... however, the block level checksums the HDD uses has false positive error rate (just like CRC16 does) and the odds of a false positive may be poor--- again, we are working in the trillions now-- up near it's limitations (I'm assuming whatever they use now scaled... but it may not have which is why more people are talking about these issues. We know it's unlikely industry has adapted to the trends evenly over the decades... it's likely become a minior problem before they are forced to change devices to a newer proprietary checksum and error correction scheme. )
Do serious work? use ECC RAM. I'm still waiting for some low power AM1 motherboard that supports ECC so I can build a ZFS server... the AM1 chip supports ECC but no motherboards do.