I might be being naive as to why this wouldn’t work, but now with digital tickets, why do stadiums even need fenced off areas outside? I can understand the way it used to be because if you didn’t employ the fences method with gates left open, you’d need to pay turnstile operators to work beyond half time. Nowadays though, why couldn’t people just exit via the turnstiles or gates even and then scan back in when they want? Nobody without a valid ticket could scan in so there’s no risk there surely.