In Japanese, translations of compound words do not necessarily equal the translation of individual characters that make up the word. So, the fact that 先生 is composed of these two characters, each of which is used separately and has a wide range of meanings, does not mean that the meaning of 先生 is the sum of these meanings.
If you look in Masuda's Japanese-English Dictionary
under Sensei, the first meaning you will come to is 'teacher'. I have been living here for 30+ years and I am called Sensei by my pupils and neighbors. This is not because I am a doctor or politician or lawyer, but because I am a teacher. I know that my neighbors refer to me as Hirodai no Sensei
: and they mean the teacher from Hiroshima University.
Of course, the word is also used as a title, but this is a separate matter from the meaning of the word. Of course, I am called Sensei by my Japanese students when I teach in my dojo, as I am by my Japanese students when I teach my university classes. The use of the Japanese term in a dojo in Indonesia is probably governed by cultural factors. Few of my Dutch students use the word during my aikido classes in the Netherlands, but some senior students believe the term should be used. I myself do not mind either way.
There is more discussion here: http://www.aikiweb.com/forums/showthread.php?t=19973