I ALMOST HAD an interview withthe man in the street last week. A taxi driver was taking me to Madison Aqure Garden. I was counting on him for the proverbial column on what the New York man in the street was thinking about the Democratic National Convention. The name on his dashboard was Alfred Mancuso. I waited for Mr. Mancuso to start the conversation, but there was dead silence in the taxi.

Finally I lost my patience. "Cat got your tongue, Mr. Mancuso?"

"How's that?" he said, stopping for a red light.

"I've been in this taxi for three minutes and you've yet to tell me what's wrong with the country."

"Don't see nuthin' wrong with it as far as I'm concerned -- everything is hunky-dory and A-OK."

"Surely you jest, sir," I said. "Are you happy with the choices for president this year?"

"Yep, I really am. When you think there are over 100 million people to choose from and the managed to find three such outstanding candidates it seems a miracle."

I looked into the mirror to see if Mr. Mancuso was putting me on.

Finally I said, "At the same time you certainly must be looking for someone to find a solution to rampant inflation that cuts through yourr take-home pay like a knife."

"I'm not for inflation," Mr. Mancuso said. "Or against it. I believe in freedom of choice. Some people may want inflation and others may not. It should be a matter of conscience."

We were only 10 blocks from Madison Square Garden and I felt my "man in the street interview" falling through my fingers.

"If the economy doesn't bother you, Mr. Mancuso, then what does?"

"That's a tough one. When you drive a taxi, see, it's very hard to get upset about something. But I'll tell you one thing about this country that bugs me."

My pad and pen were poised.

He said, "I'm not sure everyone who says to you, 'Have a nice day' really means it. Some people, when they tell you to have a nice day, are sincere, but others just say it out of habit. You can't imagine how many people get out of my cab and none of them remember a half-hour later whether they wished me a nice day or not."

"And you feel that's the thing the man in the street worries about the most?"

"I would think so. No one likes to be lied to."

We were getting terribly close to the convention hall. I made one more stab at Mr. Mancuso. "Do you have any objection to telling me whom you favor in the upcoming election?"

"Let's see. I like Reagan -- always have, ever since I saw him on 'Death Valley Days.' He seems to care for the little people in spite of being a movie star. Carter's a good man, too. He goes to church every Sunday and he loves his brother. Anderson is also a fine person. I always trust a man with white hair. But I don't think it's the role of a taxi driver to tell people what he thinks. That isn't what he's paid for. We don't know any more than anybody else -- maybe even less."

We arrived at our destination. "As spokesman for the man in the street, you're a dud," I told him.

Mr. Mancuso said, "You're the fourth reporter I took to Madison Square Garden today who said the same thing."