The more you think about it, the more impressive it is that they maintained such a far-flung and orderly bureaucracy (relatively speaking) without the printing press.
What's special about the printing press is that it makes copying cheap; the comparable Roman technology was slavery, which makes labor cheap. (In the short term.)
Slavery was present in every ancient society. The Roman empire was successful because of superior military tactics and world class fortification and infrastructure engineering-- especially roads and agriculture.
Additionally, the Romans had organizational advantages in an advanced legal and commercial code. The Romans were also extremely flexible and combined conquered local traditions with their own (Roman paganism was particularly tolerant) and by expanding Roman citizenship in ever broader circles.
That makes it even more remarkable, really, because the investment required to avoid automation is incredible. You need schools to prepare slaves as teachers (taught by slaves, of course) to teach child slaves to read and write and whatever specialist skills required by scribes. You need schools to teach the kids to read and you need slaves to produce sufficient excess food to support all the other slaves. And at the end of the day, you end up with a highly literate population of slaves in the middle of Rome, posing a significant risk to stability. Either that or they were massively efficient in their reliance on written material, which in itself would be remarkable in light of how successful they were in exporting their culture throughout the empire.
This is a great example of where the mindset of the ancient civilization is just so dramatically different than our own that it's difficult to understand their motivations.
The vast majority of Roman slaves were miserable, illiterate war captives, and generations of their offspring, working large scale farms in Italy. The instability from Roman slavery actually came from the masses of displaced Roman yeoman farmers, who could not compete with the slave agribusinesses. This was a considerable concern in ancient Rome, for cultural reasons and also because these small farmers formed the backbone of the Roman legionary forces during the Republic.
Right, and to be clear, I am addressing the scenario from the Roman perspective, not because I approve of it or whatever. Additionally, I am highlighting the notion that in order to mass produce written law and the other things necessary to successfully export a culture on massive scale over large distances, you actually do need a large population of literate slaves, which, if you're going to have slaves, is the last thing you want.
Edit: to clarify, slaves are necessary to export culture because someone has to transcribe all of the books and laws etc.
Slavery didn't export or transmit Roman culture as much as Roman citizens and traders settling conquered lands, and mixing with local elites, who adopted Roman traditions, economics, and lifestyles.
My reading of the history is that the literate Roman slaves more-or-less bought in to the system-- indeed, for the literate slave, there were paths to freedom, and some of the most trusted imperial advisers were freedmen. While slave uprisings were always a huge concern in Rome, they played no part in the eventual downfall of Rome, and the most remembered one-- Spartacus-- was of the illiterate war captive type of slave.
Why would literate slaves pose a risk to stability, necessarily?
Keep in mind that slavery for these people was nothing like the chattel slavery of the US south. Being an educated slave did mean that you had some restrictions on what you could do; it also freed you from having to worry about food and shelter, say. Similar tradeoffs have been made by salaried workers in Japan in the 70s and throughout the Western world during the industrial revolution
And even the restrictions part was ... varied. If you're a slave and your owner lives in Athens while you live in a Greek city on the Bosporus and supervise your owners business interests in the Black Sea (an actual example I recall from some of the primary sources from my Greek history classes in college), you really don't have much in the way of restrictions on you. Yes, legally you're a slave. So what? It has very little impact on your day-to-day life, at least as long as business is good.
I don't think that it's a necessity, but we're talking about the Romans, who are pretty notoriously paranoid about security issues since Rome was sacked by the Gauls. This concern seems in line with what I know of the general attitude of the average Roman citizen, especially if you're talking about slaves that came from the outer provinces, as most did in later years.
I just don't think you can ever be totally secure psychologically while you own slaves, but as I said elsewhere in this thread, there are a lot of things about the Roman mindset that are very difficult for the modern mind to identify with, so at best, this is marginally informed speculation on my part.