Having concert tickets tracked via a back-end database operated by a concert venue would mean the concert venue could arbitrarily transfer a ticket from one person to another, without the consent of the owner. If there is a dispute, there is no real way for a ticket holder to prove their case, other than their word.
But, you have to trust the venue either way. Alright, so why can't I say the same with NFTs? Don't I have to trust their words they'll allow me to join in? Can't they simply deny my enter with no excuses?
LoyceV said it;
There's no point to use a blockchain for anything tangible, as long as it relies on a single company.
There are a limited number of reasons
why a venue would deny someone access to an event they have a valid ticket for. Most venues have some kind of concession stand and/or a "gift shop" that generates revenue, so they have an incentive to have as many people inside the venue for an event as they can get.
Similarly to the above, if a venue sells 100 tickets to an event, there is the expectation that not every (current) ticket holder will show up. So if a venue expects 90% of current ticket holders to show up, they might sell 108 tickets for every 100 people worth of capacity the venue has, so they can maximize their revenue. If a venue were to sell tickets as NFTs, something like this could be easily detected.
Some entertainment events also have specific seat assignments. If you have a ticket for a specific seat, if you have an NFT ticket, you will know with certainty the venue did not issue another ticket for that same specific seat.
If you are denied admission to an event, after the fact, if you have an NFT ticket, you can prove that you actually had a valid ticket to the event if you were to complain. If you had an electronic ticket linked to the venue's private database, the venue could potentially deny that your ticket was valid.
So yes, you still need to trust the venue if you are using NFT tickets, but the level of trust needed is reduced.