How does Ticketmaster prevent people just making copies of e tickets and thier bar codes?

I buy a concert ticket, and print out the ticket on my printer. What is to prevent someone from making a color copy of that ticket, getting to the arena before me, and be sitting in my purchased seat, as I get stopped outside the arena?

They cant……..it is your responsibility to keep the information / barcode to yourself. ‘That is why the ticket is sold by a HTTPS connection (secured)

Once a specific barcode is scanned at the venue, no other identical codes are accepted.