Mark Vanhoenacker asks:

In terms of balancing America’s most cherished values, no other American memorial marking a terrorist act has struck anything like the "balance" New York has. The Oklahoma City memorial, the Flight 93 memorial, even the Sept. 11 memorial at the Pentagon: None require advance names, photo ID, or airport-style security, let alone all three. The outdoor Oklahoma City memorial—open 24/7 year-round—seems more concerned with helping visitors find nearby doggie daycare than burdening them with byzantine rules and regulations. Abroad, access to highly urban memorials in freedom-loving countries better acquainted with terrorism—Spain, the United Kingdom—is unfettered. Neither the memorial to the London July 7, 2005, attacks nor the Madrid station bombing memorial require preregistration, ID, or security checks.