Almost all the exchanges do this for the money that is why they are always quick to list shit coins because they know it's would be an opportunity for them to make fast money. This is why we have seen that Binance is very strict these days increasing the requirements for a token to be listed on there exchange. There are also exchange like OKX that like listing shit coin and later when the coin lost momentum they would delist it after they are not making money from such project.
Because Binance is the top 1 exchange and it was the first to encounter problems with the law and suffered a few billion dollar fine. Smaller exchanges are also trying to make money, but if you can’t do this based on trading volumes and the number of users, then you can try to make money on shitcoins. But most likely in the near future, against the backdrop of pressure from cryptoindustry regulators around the world, there will be a gradual displacement of shitcoins from the CEX.