Aren't they? How close can you get a vehicle to the White House or Capitol
buildings? Maybe the radius isn't 30 miles, but the restrictions are
reasonably equivalent. On the local military base, you can't park even a
motorcycle within 200 feet of any building. Let me tell ya, that's a real
pain to have to walk that extra distance to gym too.
They try to keep trucks about four blocks away, but they don't do a very good
job. If someone is determined to die for the cause they can certainly do there
by the time the Keystone Capitol Cops chase them down (got caught in a
traffic jam last year when some happless office furniture delivery truck managed
to blunder through the "no truck" zone. He'd have blown off the Senate wing if
he had a mind too...
You can still drive right up to the House/Senate office buildings. You can bet about
2 blocks from the White House itself.