> 10% hurts the same no matter your income.

10% is more just. Than a flat fine.

But 10% hurts more when you are poor and have no savings and you need that money to pay rent. For small companies is the same. Bigger corporations have more resources available to minimize that 10% impact. Power does not scale linearly with money.

But to take a percentage is a much better way than a flat fine. Flat fines are totally ineffective when applied to big corporations.