Individuals must register an account with government issued ID and the same level of KYC security as to open a bank account. This must be done a certain time in advance before the tickets for an event open.
You can only buy tickets for yourself or other already registered users whose username (or similar) you know - and only as long as you are buying a ticket for yourself too.
Some kind of exchange mechanism were a buyer can return a ticket to the pool and if someone else buys it, they get slightly less back than they paid in the first place, effectively allowing them to "resell" a ticket but at a slight loss (even if the platform takes a cut). Please don't use blockchain for this.
Maybe you can go full Chinese train tickets on this: you buy a ticket on an account backed by your government ID, and then your ID is what opens the platform gate for you. Your ID is your ticket.