Where are all the RAM drives?

Solution 1:

They are no longer common because they are not often required any more.

Now that OS's are able to easily run 64bit address spaces, you can give masses amounts of RAM to the host OS to use natively. Further, the host OS will make great use of this for caching files and all other manner of things - you don't need to set aside a RAM drive.

In addition, the speed of HDDs and, of course, SDDs means that you get rather less benefit.

So volatile RAM drives are reduced to a highly specialist role. They are expensive and cause problems if they do not have sufficient power backup so they are only used in special cases.