in a normal world - excessive taxes on private vehicles are countered by a well established transport system that can be used by common people OR a very well developed manufacturing system for private vehicles.
Now that you have realized that you are not in the normal world because you are in Pakistan - where the transport system is no more than paved cow trails and the remaining scrap metal of the railway that was left by the British Raj is being used - is still being propped up on a high dice and ergo used as "counter offer" by the people who paid a crore or so to get appointed to seats in governing/deciding positions.
The issue is that just cheaping out cars will not work as the adult literacy rate, GDP, etc etc (insert college education sounding terms here) - are down the drain. A simple example is look at the mass bus transport system that was in Karachi, there were proper buses (no matter how shabbily built on aged platforms - but they were HD chassis) - they got replaced by elongated rickshaws which were being used as buses. - Such act already proves the point that there is no concept of proper transport or even concerns of safety for anyone. e.g. A kid high on smoke and stunt movie scenes in his brand new "accord/civic/corolla etc" can barrel down a road at 200 km/h and crash into these rickshaw killing all 8+1 people in it and nothing at all will happen - no questions or even a damn would be given.
My point is that there was no "designed and developed" system implemented or followed - after 1947 - a bunch of people from India were airlifted and dropped in Karachi to run the "guvmint" on whatever could be salvaged from the old as the country was half filled with farmers and the remaining were immigrants in poor shape.
Because of the love of "shortcut/jugaar/chalta hai" nature of every other person in Pakistan and oversimplifcation - (even in education) you have what you see today. Every other book/law is either copied from the Raj or is written for some vested interests of some big businessmen (e.g. Agriculture). You will be surprised to see the applications of duty according to customs - e.g. engine tachometer, seat arrest belts, side runners etc.
The above make sense if you imagine it with British rule, you would not be subjected to these if you had British machines, Such high taxations were applied to "imports" e.g. if you were to buy a Mercedes Benz coachbuild - prepare to drain your bank (do you see many prewar german cars in Pakistan/India?) - the answer would be no as they were taxed on insane levels.
What you have today is a carbon copy of that old system. Its a sort of catastrophe because the variables to affect have changed drastically.
Now unless you are willing to reboot the system and write a new one or atleast get the basics correct like education, manufacturing, transport etc - this will never change.
ergo - have a cup of chai and enjoy - Eid mubarak.