It's a free market.
If you find an exchange that has their fees dropped. Use it. It will incentivize other companies to do the same.
And the owner of that exchange know how much will be enough fee for them to earn and attractive to users to get more traders.
There are exchnage with low fee bur the questions is if the volume of exchange is enough and how secure that exchange is.
Why would the volume matter? It has nothing to do with trading or withdraw fees. You don't need high volume to trade on an exchange. That's not how it works. You only need volume when its the entire market. A small exchange can do well with a low volume of they give good customer care and run smoothly.