If Houses Were Built to Current Code, Would We Need To Drip Faucets?

When I lived up North in an old house built in the 1930's we didn't need to run the faucets whenever the temperatures dropped below freezing, which was most of January and February. So why do houses built in the 1970's in Dallas need to have faucets dripping when it gets below freezing? What about new homes built in the last few years in Dallas; is faucet dripping required with them? If feels like a properly designed house, built to code in Dallas, shouldn't need to have faucets dripping.