Exchanges were the key support system for Cryptocurrency network, this makes them have a big control over the volumes. Fake trade volumes were once inspected and it made a huge crash to the entire market, and this isn't controllable. Even there were paid services from exchanges to show high volumes on specific assets.
Many countries already make a big threat to those who are responsible for manipulating the trade volume, and if theres a regulation a strong like this, fake volumes can be lessen. But its true, exchanges are being paid for this and we dont know if top exchanges are also doing this, its possible of course.
Well even if they are doing, at least they have solid volume underneath it.
Small exchanges doing that is very obvious. You see orders doesn't move but transactions coming out of nowhere. It is very easy to spot on.