For some of you saying she shouldn't be forced to acquire and use a passport is absurd. You are acting like she actually still has full control of the UK like the monarchs of the past. Parliament is in control, it's kind of like how our government works. We have a congress to help pass and regulate law, and they have the most power. Then there is the president who is in control of some of the legislative portions of the job and dealing with the military and foreign affairs. The queen is just a longer serving "president" at this moment and time. Our president, Barrack Obama uses a passport. So why does the queen not deal with this same issue.
Apparently, everyone else in the Royal Family is required to carry a passport, except the queen herself. While traveling out of country, where not ever person will recognize the Queen, this could pose problems. The time and expense in security checks to identify the Queen in certain situations, would proved costly.
The purpose of a passport is to identify a traveler. Queen Elizabeth is instantly recognizable by people all over the world. She is also a head of state, and heads of state always enjoy special diplomatic privileges when it comes to international travel. No-one is wronged by her not needing a passport.
Queen Elizabeth II is one of the most recognisable people on the planet, as her face is on many bank notes and postage stamps all over the world. All her movements are official, and I find it hard to believe there would be a situation where she would arrive to travel without those involved having been informed before hand. For her a passport would be little more than ceremony. It's better to save the money!
No head of state is required to produce a passport when travelling. Do you really think when Obama gets off a plane in Berlin they ask for his passport? No. Nor should they. There is a certain level of respect afforded to all Heads of State. This is one of them.
When a person is a queen, they have rights that other people do not have. In this case, she has had to be famous her entire life. She has had to be prim and proper, and have the media and the news report on everything she has ever done. It is not unfair that a few perks go with that.