hitman levels question

Hi,
so I have been trying to play hitman this and last round and there is one thing that I dont really understand.
why is hitmans level 4 so ridiculously hard compare to every other profession?

every profession for lever 4 needs to do
+-40 gang robberies
+-400 single robberies
and have 4500 respect

except hitman has extra 30 kills...

I understand that hitman is the hardest profession and has 0% chance of winning top respect but leveling up as a hitman is just weird compare to other professions.

just to point out from level 3 to 4 you need to get 27 kills but from level 4 to 5 you need just 20 and until level 10 you need 25kills for each level
I really dont understand why there is such a crippling condition for getting level 4