Audiobooks aren't really a good solution to be honest. Reading / writing literacy are the basis of scholarship. We have centuries of research and examples that we've turned our back on that efficient learning happens only when you can unlock good literacy skills. Specifically the aspect of reading/physical writing/sublingualization is a cornerstone of comprehension of complex ideas. With something like Marxism that's based on understanding both technical and archaic language and social constructs it becomes really hard. There are tons of self professed Marxists that couldn't tell you what commodity fetishism actually means in simple terms.
Great example is the Communist Manifesto itself, meant to be a pamphlet for factory workers in the 19th century, but is typically a mildly difficult text to approach for the average person today.
Audiobooks can replace something like pleasure reading where you're just reading pulp garbage, but they're not really a good replacement for learning.
You're talking from a relative position of understanding of these concepts. You're not talking from a blank slate. Even in professional environments that I've been in where everyone went to college and theoretically is fully literate, you would have trouble getting people to retain these concepts even if you used friendlier technical language. You're overestimating the amount of time it takes to actually achieve understanding, there are people on this site that constantly mix up these words and concepts, have a hard time applying them to the real world and misapply them regularly and are self professed Marxists. You're also mistaking cultural policing of agreeing/using these concepts for understanding of them. Just think about how many people in America agree with capitalism but can't adequately explain what capitalism is. They agree with freedom but don't have a working definition or framework of what freedom means. On a societal level this often becomes bromides. My parents and grandparents read Marx in school but couldn't give you an accurate basic run down of Marxist concepts.
Marxism isn't some magical thing. There were plenty of people in the USSR that also didn't understand the system they existed under and it's concepts but reflexively or sheepishly agreed with it.