To pick one extremely important example - financial services. For example: https://www.bitsaboutmoney.com/archive/the-waste-stream-of-consumer-finance/ - the system is structured in such a way as to keep poor people in the poverty trap in a way that simply doesn't happen for middle class people.

They are simply more profitable when kept in the trap - and the banks and credit card companies don't give a damn how much human misery and damaged mental health is caused by that squeezing out of that last bit of profit from desperate people. 3/