The reason that "get" does not always indicate immediacy is because the word has multiple meanings and uses in English. While one of the uses of "get" can indicate a sense of urgency or promptness, such as in the examples I gave earlier, there are many other contexts in which "get" is used that do not necessarily convey this sense. For example, "get" can be used to indicate possession or acquisition of something, as in "I got a new car". In this case, there is no connotation of immediacy or promptness - the speaker is simply stating that they acquired a new car at some point in the past. Similarly, "get" can be used to indicate a change of state or condition, as in "The milk has gone bad - we need to get some fresh milk". In this case, there is a sense of urgency or promptness, but it is not related to the use of "get" itself - rather, it is because the milk has gone bad and needs to be replaced. Therefore, the reason that "get" does not always indicate immediacy is simply because the word has a wide variety of meanings and uses in English, and its use depends on the specific context in which it is being used.