Since the male vehicle is meant to protect, provide and lead, it is considered to be a superior vehicle. Otherwise he could not fulfill this function. And since a woman is meant to be protected and dependant, her vehicle is an inferior one. So it is simply meant in bodily terms, which does not affect the equality on the level of the soul, nor their qualification for spiritual life.
Srila Prabhupada explains this in a SB lecture on the 3rd of August 1968: "I was student of psychology in my college life. Dr. Urquhart said, I remember still, that the brain substance has been found up to 64 ounce, while brain substance of woman has been found, highest, 34 ounce. Therefore woman class (laughs) is not so intelligent as man. There is no question of competition. It is actual, scientific fact. But one thing I must explain here. So far spiritual life is concerned, it does not depend on the material brain substance. It is different thing. It is spiritual platform. It has nothing to do with this bodily construction.
You must remember. We don't make any distinction that a man can be better Krsna conscious than woman. No. A woman can be better Krsna conscious because they are very simple. They can accept any religious system. Generally the women, they accept it because they are very simple. They have no crooked mind. Sometimes they are exploited therefore. So in the spiritual platform there is no such distinction, although in the material... Just like the bodily construction of man is different from woman, similarly, the brain substance may be also different, but that does not disqualify any woman for spiritual advancement in Krsna consciousness....."
The fact that women are less intelligent refers to material intelligence, which is one of the material elements of the subtle body. As a rule men also have bigger feet. We usually don't get agitated hearing this, since we don't identify so much with our feet. It's only the feet. But with our intelligence we identify much more, and we are so proud of being very intelligent. So therefore our ego is protesting when it comes to us women being less intelligent. In order to return back to Godhead we have to dissolve the subtle body of mind, intelligence and false ego. It can almost be considered an advantage to have a smaller subtle body - less work to dissolve it....!
If both men and women play their roles and execute their purifying duties within Krsna consciousness according to the vehicle they are driving, it is the perfect arrangement to make spiritual progress and ultimately qualify oneself to go back to Godhead. It is Krsna's Divine system to give us stability and harmony in this world in order to create a solid foundation for spiritual life.
The word hierarchy comes from Greek and means 'Divine order', with Krsna being on the very top of this order. So Krsna has set up a Divine order, so that everything functions in harmony and peace, and all human beings are
perfectly taken care off.
Once we understand that Krsna is on the top of the hierarchy, then the terms of 'higher' or 'lower' will not create a competitive mood. The brahmanas are considered to be 'higher' than the sudras, the Sannyasis are considered to
be 'higher' than the other ashrams, men are considered to be higher than woman. Are they competing with each other? Of course not, because being 'higher' means giving protection, care and shelter to those who are 'lower'.
However, when Krsna is removed from the top of the hierarchy, then somebody else is trying to take His place, and the Divine order easily turns into exploitation and suppression, and of course the aspects of envy and
competition enter. So then the terms of 'higher' and 'lower' create the mood of disrespect, competition and abuse.
However, when Krsna is on the top of the hierarchy, and still we women feel inferior to men and compete, then this would indicate that we are on the bodily platform, identifying with the body and forgetting that the equality is there on the level of the soul.
As we all know, in these modern days there has been an increase of violence and aggression towards women. We can understand this to be the direct result of the fact that women don't receive protection any longer. And of course, ladies can only be protected if they desire to receive protection. It also includes that we have to give up our independance - the price to be payed in order to receive protection. The whole idea of equality of men and women makes this difficult, if not to say impossible....
Your servant, Devaki dd