Totalitarianism is a specific feature of modern authoritarian regimes, one that not all authoritarians use. The intent is to create a system in which the behavior, beliefs, and even the very thought patterns of citizens are controlled by the government: through propaganda, elimination of opposition, and vast surveillance. Totalitarianism is extremely time and effort consuming; it implies degrees of Machiavellianism and paranoia that not every potential leader shares.
Most authoritarian leaders (kings, emperors, dictators, and such) are content to rest on institutions. They anticipate that average citizens will naturally fall in line with establish rule, respecting the institution of authority, and they are not usually disappointed. People have a (fortunate or unfortunate) tendency to go along with the status quo; I'm reminded of the case of Emperor Norton, who declared himself King of the US (and Protector of Mexico), and was thoroughly indulged in that pretense by the people of San Francisco for a short time. A typical king doesn't think twice about whether his citizens are loyal, because he is the king and citizens are loyal to kings. There is simply no question to it.
A totalitarian, by contrast, is disconcerted by the concept of disloyalty. He sees everyone as a potential threat, everyone as a potential enemy, and thus goes to excessive lengths to discover, identify, and root out anyone who might be disloyal. It is an intrinsically consuming, paranoid worldview that calls for ever-increasing, every-paranoid monitoring of practicality everyone.
Most dictators are not totalitarians because:
- they lack the bureaucratic technology to truly surveil the population as a whole, and...
- they implicitly assume that the typical citizen loves them and loves their rule, so that there is no need to fear the populace as a whole
Most dictators lack that paranoid strain in which everyone is a potential threat, and thus everyone must be monitored, so they lack any effective reason to engage in the complex, resource-intensive, and extremely difficult task of watching everyone. Better to spend time and money acquiring new weapons than building large databases of more-or-less uninteresting citizens.