Scenario 1: Number of available tickets is not constant. For that day 300 tickets sold to 300 different players. So every player has 1/300 chance of winning. In this scenario, you can not make it provably fair because you cannot know how many tickets will attend to lottery in the beginning of the day.
Actually, it's quite possible. Check:
https://www.pevpot.com/provably-fair for a concrete example
(PevPot never knows how many tickets will be sold, but has no problems being provably fair. There's a few different ways to do this too, I believe)
