Can't you just read "3 MB of RAM" as a large amount of some scarce tech resource and move on?
What if you got a on-chip compression algorithm so advanced that you can fit a world in a few MB and now with corporations controlling memory distribution, 3MB of high compression memory is highly valuable in the black market.
"High compression memory" is immersion-breaking magic. There are hard mathematical limits to how much you can compress things (Kolmogorov complexity), and every lossless compression algorithm necessarily increases the size of some inputs (pigeonhole principle). It's much simpler to assume that "M" is slang for some bigger unit.
We already have the real life example of people using "mega" (10^6) as slang for "mebi" (2^20).