Yes you are correct Venus is also the lord of Taurus, however it is not the most powerful sign of Venus. Libra is the most powerful sign of Venus. It is absolutely incorrect to say that people with debilitated Sun will not get Govt Jobs. I have seen that many people with debilitated Sun have got good Govt jobs.
I again repeat it is the nature of the sign and its ruling planet where other planets get exalted or debilitated. I will try to explain again, the Sun is know for its cruelty, Authority, independence that it can only get in Aries the sign of Mars which is known for commanding, strength and courage. The cruelty of Sun is backed by command and courage of Mars. Therefore only in the sign of Aries it gets exalted. In the sign of Libra , Sun the cruelty, command gets weakened as it enters the sign of peace and love.
I hope it is clear now. If you really want to learn more just leave the useless astrology writers and read the good ones and most importantly have a very open mind.