Why do agents insist on not listing a property at a price?

Respected journalist and well know funny man Mike O`Connor in thie weeks edition (March 2-3 2013) of the Courier mal QWEEKEND lambasts the practice with a story of his own experience and asks the cogent question as to how many buyers walk away in fruestration because they ar enot prpeared to play the real estate game - talk about road rage, this is property range to the max!

The journey began, like so many of life's adventures, in bed. It was Saturday morning, the best time of the week, and I was stretched out with my head propped against the pillows. I'd been downstairs and returned with tea and toast and we were both reading the 'newspapers.

"That's nice," said my partner, an observation I acknowledged with a grunt meant to indicate: "Leave me alone. I'm reading".
"What do you think?" she persisted, so I looked up and saw a photograph of a house. "Very nice," I said and went back to reading."We should have a look," she said. I should have replied: "Never! Madness lies that way", but I was drugged by the bliss of the morning and surrendered too easily.
"Why?" I said, when we pulled-up at the address, "are we looking at a house which is for sale when we have no plans to move?"
"Just curious," she said. - - --
"I suppose there's no harm in looking," I said, words which, along with "Keep reversing. There's plenty of room"- and '1 didn't know you were pregnant", can presage disaster.
It was a very, pleasant house, closer to the city than where we are and with the requisite number of bedrooms. How much? Silly me. No-one puts a price on a house in Brisbane any more. It's like a television-quiz show. You have to guess how much is being asked-. Offer too little and you get the "I think you're looking in the wrong suburb" - look, too much and the agent will tie you to - a chair and run and fetch the owner.
When I've asked the price of properties, I've been told how much the one up the road sold for and how much they got for the one across the street, but never the price being asked for the one in which we are standing. It's a secret between the agent and the owner and is not to be shared with people who might be interested in buying. I presume this is because they know what it's worth but refuse to utter the figure in the hope that someone will come and offer them more.
I wonder how any potential buyers walk away in frustration because they are not prepared to play the great real estate guessing game? If you buy a car it has a price. If you book a hotel room, it has a price. If you buy a suit, you know how much is being asked, but not with houses.
It's irritating but we're on the treadmill now, it one moment of weakness - "it can't hurt to look - --being enough to trigger a low-level addiction to house inspections. You begin thinking that it might actually be-nice to move closer to the city and the new surrounds would somehow be life-changing. Once you've looked at one house, you have to - look at more.
Why? To compare. "But we're not moving," I insist. "But we should know what's around if we do decide to move," she replies.