The events they create are for the purpose of raising awareness; the more people who participate in that event, the more news about them will spread. That's how they will reach more people, and what they are about to launch will be discussed even before they finally launch.
And if they are ever going to have a token for the exchange, using it to reward those who participate in that event can also be a means to increase the number of token holders.
As for trust, I don't go for new exchanges just like that unless they are the only choice I have; if not, I need to see them prove their worth by reading through the reviews of those who might have honestly used them.
What do you mean? what are those events?
I guess it should be events like cryptodrop, airdrop, contest, shilling or any kind of activity that can help them gain awareness.