Stadiums can ban flags to protect advertising revenue
Safety and security are often cited as the official reasons for removing fan banners, but the underlying cause is frequently commercial.
Football fans attending major international tournaments often find their traditional displays of support restricted by strict stadium regulations. At the World Cup opener at Dallas Stadium, officials advised supporters that flags would be confiscated if they were hung over LED advertising boards. While FIFA sources frequently cite safety and security reasons for such bans, the primary driver is often the protection of high-value digital real estate.