But those costs are much less than the network fees since they're done in bulk instead of per transaction. Credit card processing fees are ~3%, so for every $1k in sales, you pay ~$30, whereas going to the bank is a fixed cost and merely takes time and can be scheduled when it's cheapest to do. So dealing with cash scales well since it has a fixed cost, whereas credit/debit gets more expensive (compared to cash) as revenue increases.