Equality Society and Mathematics

I always try to analyse day to day things from my perspective. I always wonder about so called equality. Whether in mathematics or in society.  Let's try to understand it better with simple examples.
If somebody breaks a red-light what is the fine ?? let's say 200 RS. and its same for all people .
This is so called equality from our law. I simply don't agree. Because 200 RS doesn't value same for all people. A person earning million and a person earning thousands do have same feeling for 200 RS ???
NO right?
 Then how can we say law is same for all??
That's why I am always a fan of %[Percentage] in mathematics. It gives the real feel of equality for humans. If you spend 10% of your income. No matter how much you earn your feeling and a person whose income is 40% of your income will feel the same. Isn't it??
   So in my opinion for any service which is supposed to be in the category of equality  should  contain a equation like
                                             y= z*x +k;
Where

• y= Service cost
• z= constant variable dependent on service in percentage , z>0 [Same for all for one service]
• x= Annual or monthly income. x>=0
• k= Constant dependent on service,K>0

So we will reach a graph roughly like

Now let's set an expected real working example of redlight jump now with the above equation.

As jumping redlight is a serious offence then I can set this equation as 

y= 1% of monthly income +200 RS.

So a person earning 10000 as monthly salary will end up paying the fine as :  1% of 10000+200=300

and a person earning 100000 as monthly salary will end up paying the fine as :  1% of 100000+200=1200

This way is we can spread equality. I have no idea is there such rule exits?? If know such rule anywhere in world let me know.

I want to know your opinion in comments. Feel free to say whatever comes in your mind.