When it comes to banks, there is also a tier where fees are waived for high value customers. For example, checking, atm, wires, are free if you have $50k or more in your checking account.
There is a certain amount of overhead in servicing an account whether it has $5 in it or $500,000 in it. A $5 account doesn't give the bank much to loan while a $500,000 gives the bank lots of money to loan out. So the bank would rather have 100 $500k accounts than 100 $5 accounts. The fees help make the bank willing to maintain the $5 accounts.
